File: perllocale.html

package info (click to toggle)
perl-doc-html 5.18.2-1
  • links: PTS
  • area: main
  • in suites: jessie, jessie-kfreebsd
  • size: 38,816 kB
  • ctags: 26,804
  • sloc: xml: 36; makefile: 10
file content (1512 lines) | stat: -rw-r--r-- 105,741 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
  <title>perllocale - perldoc.perl.org</title>
  <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
  <meta http-equiv="Content-Language" content="en-gb">
  <link rel="search" type="application/opensearchdescription+xml" title="Search perldoc.perl.org" href="/static/search.xml"/>
  <link href="static/css-20100830.css" rel="stylesheet" rev="stylesheet" type="text/css" media="screen">
  <link href="static/exploreperl.css" rel="stylesheet" rev="stylesheet" type="text/css">
</head>

<body onLoad="perldoc.startup();" onPageShow="if (event.persisted) perldoc.startup();">
    <div id="page">
      
      <div id="header">
	<div id="homepage_link">
	  <a href="index.html"></a>
	</div>
	<div id="strapline">
	  Perl Programming Documentation
	</div>
	<div id="download_link" class="download">
	  <a href="http://www.perl.org/get.html">Download Perl</a>
	</div>
	<div id="explore_link" class="download">
	  <a id="explore_anchor" href="#">Explore</a>
	</div>
      </div>
      
      <div id="body">
        <div id="left_column">
          <div class="side_group">
            
	    <div class="side_panel doc_panel">
              <p>Manual</p>
              <ul>
                <li><a href="index-overview.html">Overview</a>
                <li><a href="index-tutorials.html">Tutorials</a>
                <li><a href="index-faq.html">FAQs</a>
                <li><a href="index-history.html">History / Changes</a>
                <li><a href="index-licence.html">License</a>
              </ul>
            </div>
            <div class="side_panel doc_panel">
              <p>Reference</p>
              <ul>
                <li><a href="index-language.html">Language</a>
                <li><a href="index-functions.html">Functions</a>
                <li><a href="perlop.html">Operators</a>
                <li><a href="perlvar.html">Special Variables</a>
                <li><a href="index-pragmas.html">Pragmas</a>
                <li><a href="index-utilities.html">Utilities</a>
                <li><a href="index-internals.html">Internals</a>
                <li><a href="index-platforms.html">Platform Specific</a>
              </ul>
            </div>
            <div class="side_panel doc_panel">
              <p>Modules</p>
              <ul>
		<li>
		
                
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		
                  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		
                  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		
                  
		
                  
		    
		  
		
                  
		
                  
		
		
                    <a href="index-modules-A.html">A</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-B.html">B</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-C.html">C</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-D.html">D</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-E.html">E</a>
                    
                      
                        <li>
                      
                    
                
                    <a href="index-modules-F.html">F</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-G.html">G</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-H.html">H</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-I.html">I</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-L.html">L</a>
                    
                      
                        <li>
                      
                    
                
                    <a href="index-modules-M.html">M</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-N.html">N</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-O.html">O</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-P.html">P</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-S.html">S</a>
                    
                      
                        <li>
                      
                    
                
                    <a href="index-modules-T.html">T</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-U.html">U</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="index-modules-X.html">X</a>
                    
                
              </ul>
            </div>
            
	      <div class="side_panel doc_panel">
		<p>Tools</p>
		<ul>
		  <li><a href="preferences.html">Preferences</a>
		</ul>
	      </div>
            
          </div>
        </div>
        <div id="centre_column">
          <div id="content_header">
            <div id="title_bar">
              <div id="page_name">
                <h1>perllocale</h1>
              </div>
              <div id="perl_version">
                Perl 5 version 18.2 documentation
              </div>
              <div class="page_links" id="page_links_top">
                <a href="#" onClick="toolbar.goToTop();return false;">Go to top</a>
		
              </div>
	      <div class="page_links" id="page_links_bottom">
		
                  <a href="#" id="page_index_toggle">Show page index</a> &bull;
		
                <a href="#" id="recent_pages_toggle">Show recent pages</a>		
	      </div>
	      <div id="search_form">
		<form action="search.html" method="GET" id="search">
		  <input type="text" name="q" id="search_box" alt="Search">
		</form>
	      </div>
            </div>
            <div id="breadcrumbs">
                
    <a href="index.html">Home</a> &gt;
    
      
        <a href="index-language.html">Language reference</a> &gt;
      
    
    perllocale
  

            </div>
          </div>
          <div id="content_body">
	    <!--[if lt IE 7]>
 <div class="noscript">
   <p>
     <strong>It looks like you're using Internet Explorer 6. This is a very old
     browser which does not offer full support for modern websites.</strong>
   </p>
   <p>
     Unfortunately this means that this website will not work on
     your computer.
   </p>
   <p>
     Don't miss out though! To view the site (and get a better experience from
     many other websites), simply upgrade to
     <a href="http://www.microsoft.com/windows/Internet-explorer/default.aspx">Internet
Explorer 8</a>
     or download an alternative browser such as
     <a href="http://www.mozilla.com/en-US/firefox/firefox.html">Firefox</a>,
     <a href="http://www.apple.com/safari/download/">Safari</a>, or
     <a href="http://www.google.co.uk/chrome">Google Chrome</a>.
   </p>
   <p>
     All of these browsers are free. If you're using a PC at work, you may
     need to contact your IT administrator.
   </p>
 </div>
<![endif]-->
	    <noscript>
	      <div class="noscript">
	      <p>
                <strong>Please note: Many features of this site require JavaScript. You appear to have JavaScript disabled,
	        or are running a non-JavaScript capable web browser.</strong>
	      </p>
	      <p>
		To get the best experience, please enable JavaScript or download a modern web browser such as <a href="http://www.microsoft.com/windows/Internet-explorer/default.aspx">Internet Explorer 8</a>, <a href="http://www.mozilla.com/en-US/firefox/firefox.html">Firefox</a>, <a href="http://www.apple.com/safari/download/">Safari</a>, or <a href="http://www.google.co.uk/chrome">Google Chrome</a>.
              </p>
	      </div>
	    </noscript>

	    <div id="recent_pages" class="hud_container">
	      <div id="recent_pages_header" class="hud_header">
		<div id="recent_pages_close" class="hud_close"><a href="#" onClick="recentPages.hide();return false;"></a></div>
		<div id="recent_pages_title" class="hud_title"><span class="hud_span_top">Recently read</span></div>
		<div id="recent_pages_topright" class="hud_topright"></div>
	      </div>
	      <div id="recent_pages_content" class="hud_content">
	      </div>
	      <div id="recent_pages_footer" class="hud_footer">
		<div id="recent_pages_bottomleft" class="hud_bottomleft"></div>
		<div id="recent_pages_bottom" class="hud_bottom"><span class="hud_span_bottom"></span></div>
		<div id="recent_pages_resize" class="hud_resize"></div>
	      </div>
	    </div>
  
	    <div id="from_search"></div>
            <h1>perllocale</h1>


  <!--    -->
<ul><li><a href="#NAME">NAME</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#WHAT-IS-A-LOCALE">WHAT IS A LOCALE</a><li><a href="#PREPARING-TO-USE-LOCALES">PREPARING TO USE LOCALES</a><li><a href="#USING-LOCALES">USING LOCALES</a><ul><li><a href="#The-use-locale-pragma">The use locale pragma</a><li><a href="#The-setlocale-function">The setlocale function</a><li><a href="#Finding-locales">Finding locales</a><li><a href="#LOCALE-PROBLEMS">LOCALE PROBLEMS</a><li><a href="#Temporarily-fixing-locale-problems">Temporarily fixing locale problems</a><li><a href="#Permanently-fixing-locale-problems">Permanently fixing locale problems</a><li><a href="#Permanently-fixing-your-system's-locale-configuration">Permanently fixing your system's locale configuration</a><li><a href="#Fixing-system-locale-configuration">Fixing system locale configuration</a><li><a href="#The-localeconv-function">The localeconv function</a><li><a href="#I18N%3a%3aLanginfo">I18N::Langinfo</a></ul><li><a href="#LOCALE-CATEGORIES">LOCALE CATEGORIES</a><ul><li><a href="#Category-LC_COLLATE%3a-Collation">Category LC_COLLATE: Collation</a><li><a href="#Category-LC_CTYPE%3a-Character-Types">Category LC_CTYPE: Character Types</a><li><a href="#Category-LC_NUMERIC%3a-Numeric-Formatting">Category LC_NUMERIC: Numeric Formatting</a><li><a href="#Category-LC_MONETARY%3a-Formatting-of-monetary-amounts">Category LC_MONETARY: Formatting of monetary amounts</a><li><a href="#LC_TIME">LC_TIME</a><li><a href="#Other-categories">Other categories</a></ul><li><a href="#SECURITY">SECURITY</a><li><a href="#ENVIRONMENT">ENVIRONMENT</a><ul><li><a href="#Examples">Examples</a></ul><li><a href="#NOTES">NOTES</a><ul><li><a href="#Backward-compatibility">Backward compatibility</a><li><a href="#I18N%3aCollate-obsolete">I18N:Collate obsolete</a><li><a href="#Sort-speed-and-memory-use-impacts">Sort speed and memory use impacts</a><li><a href="#write()-and-LC_NUMERIC">write() and LC_NUMERIC</a><li><a href="#Freely-available-locale-definitions">Freely available locale definitions</a><li><a href="#I18n-and-l10n">I18n and l10n</a><li><a href="#An-imperfect-standard">An imperfect standard</a></ul><li><a href="#Unicode-and-UTF-8">Unicode and UTF-8</a><li><a href="#BUGS">BUGS</a><ul><li><a href="#Broken-systems">Broken systems</a></ul><li><a href="#SEE-ALSO">SEE ALSO</a><li><a href="#HISTORY">HISTORY</a></ul><a name="NAME"></a><h1>NAME</h1>
<p>perllocale - Perl locale handling (internationalization and localization)</p>
<a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
<p>In the beginning there was ASCII, the "American Standard Code for
Information Interchange", which works quite well for Americans with
their English alphabet and dollar-denominated currency.  But it doesn't
work so well even for other English speakers, who may use different
currencies, such as the pound sterling (as the symbol for that currency
is not in ASCII); and it's hopelessly inadequate for many of the
thousands of the world's other languages.</p>
<p>To address these deficiencies, the concept of locales was invented
(formally the ISO C, XPG4, POSIX 1.c "locale system").  And applications
were and are being written that use the locale mechanism.  The process of
making such an application take account of its users' preferences in
these kinds of matters is called <b>internationalization</b> (often
abbreviated as <b>i18n</b>); telling such an application about a particular
set of preferences is known as <b>localization</b> (<b>l10n</b>).</p>
<p>Perl was extended to support the locale system.  This
is controlled per application by using one pragma, one function call,
and several environment variables.</p>
<p>Unfortunately, there are quite a few deficiencies with the design (and
often, the implementations) of locales, and their use for character sets
has mostly been supplanted by Unicode (see <a href="perlunitut.html">perlunitut</a> for an
introduction to that, and keep on reading here for how Unicode interacts
with locales in Perl).</p>
<p>Perl continues to support the old locale system, and starting in v5.16,
provides a hybrid way to use the Unicode character set, along with the
other portions of locales that may not be so problematic.
(Unicode is also creating <code class="inline"><span class="w">CLDR</span></code>
, the "Common Locale Data Repository",
<a href="http://cldr.unicode.org/">http://cldr.unicode.org/</a> which includes more types of information than
are available in the POSIX locale system.  At the time of this writing,
there was no CPAN module that provides access to this XML-encoded data.
However, many of its locales have the POSIX-only data extracted, and are
available at <a href="http://unicode.org/Public/cldr/latest/">http://unicode.org/Public/cldr/latest/</a>.)</p>
<a name="WHAT-IS-A-LOCALE"></a><h1>WHAT IS A LOCALE</h1>
<p>A locale is a set of data that describes various aspects of how various
communities in the world categorize their world.  These categories are
broken down into the following types (some of which include a brief
note here):</p>
<ul>
<li><a name="Category-LC_NUMERIC%3a-Numeric-formatting"></a><b>Category LC_NUMERIC: Numeric formatting</b>
<p>This indicates how numbers should be formatted for human readability,
for example the character used as the decimal point.</p>
</li>
<li><a name="Category-LC_MONETARY%3a-Formatting-of-monetary-amounts"></a><b>Category LC_MONETARY: Formatting of monetary amounts</b>
<p>&#xa0;</p>
</li>
<li><a name="Category-LC_TIME%3a-Date%2fTime-formatting"></a><b>Category LC_TIME: Date/Time formatting</b>
<p>&#xa0;</p>
</li>
<li><a name="Category-LC_MESSAGES%3a-Error-and-other-messages"></a><b>Category LC_MESSAGES: Error and other messages</b>
<p>This for the most part is beyond the scope of Perl</p>
</li>
<li><a name="Category-LC_COLLATE%3a-Collation"></a><b>Category LC_COLLATE: Collation</b>
<p>This indicates the ordering of letters for comparison and sorting.
In Latin alphabets, for example, "b", generally follows "a".</p>
</li>
<li><a name="Category-LC_CTYPE%3a-Character-Types"></a><b>Category LC_CTYPE: Character Types</b>
<p>This indicates, for example if a character is an uppercase letter.</p>
</li>
</ul>
<p>More details on the categories are given below in <a href="#LOCALE-CATEGORIES">LOCALE CATEGORIES</a>.</p>
<p>Together, these categories go a long way towards being able to customize
a single program to run in many different locations.  But there are
deficiencies, so keep reading.</p>
<a name="PREPARING-TO-USE-LOCALES"></a><h1>PREPARING TO USE LOCALES</h1>
<p>Perl will not use locales unless specifically requested to (see <a href="#NOTES">NOTES</a> below
for the partial exception of <code class="inline"><a class="l_k" href="functions/write.html">write()</a></code>).  But even if there is such a
request, <b>all</b> of the following must be true for it to work properly:</p>
<ul>
<li>
<p><b>Your operating system must support the locale system</b>.  If it does,
you should find that the setlocale() function is a documented part of
its C library.</p>
</li>
<li>
<p><b>Definitions for locales that you use must be installed</b>.  You, or
your system administrator, must make sure that this is the case. The
available locales, the location in which they are kept, and the manner
in which they are installed all vary from system to system.  Some systems
provide only a few, hard-wired locales and do not allow more to be
added.  Others allow you to add "canned" locales provided by the system
supplier.  Still others allow you or the system administrator to define
and add arbitrary locales.  (You may have to ask your supplier to
provide canned locales that are not delivered with your operating
system.)  Read your system documentation for further illumination.</p>
</li>
<li>
<p><b>Perl must believe that the locale system is supported</b>.  If it does,
<code class="inline">perl -V:d_setlocale</code> will say that the value for <code class="inline"><span class="w">d_setlocale</span></code>
 is
<code class="inline"><span class="w">define</span></code>
.</p>
</li>
</ul>
<p>If you want a Perl application to process and present your data
according to a particular locale, the application code should include
the <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 pragma (see <a href="#The-use-locale-pragma">The use locale pragma</a>) where
appropriate, and <b>at least one</b> of the following must be true:</p>
<dl>
<dt>1</dt><dd>
<p><b>The locale-determining environment variables (see <a href="#ENVIRONMENT">ENVIRONMENT</a>)
must be correctly set up</b> at the time the application is started, either
by yourself or by whomever set up your system account; or</p>
</dd>
<dt>2</dt><dd>
<p><b>The application must set its own locale</b> using the method described in
<a href="#The-setlocale-function">The setlocale function</a>.</p>
</dd>
</dl>
<a name="USING-LOCALES"></a><h1>USING LOCALES</h1>
<a name="The-use-locale-pragma"></a><h2>The use locale pragma</h2>
<p>By default, Perl ignores the current locale.  The <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>

pragma tells Perl to use the current locale for some operations.
Starting in v5.16, there is an optional parameter to this pragma:</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span><span class="sc">;</span></li></ol></pre><p>This parameter allows better mixing of locales and Unicode, and is
described fully in <a href="#Unicode-and-UTF-8">Unicode and UTF-8</a>, but briefly, it tells Perl to
not use the character portions of the locale definition, that is
the <code class="inline"><span class="w">LC_CTYPE</span></code>
 and <code class="inline"><span class="w">LC_COLLATE</span></code>
 categories.  Instead it will use the
native (extended by Unicode) character set.  When using this parameter,
you are responsible for getting the external character set translated
into the native/Unicode one (which it already will be if it is one of
the increasingly popular UTF-8 locales).  There are convenient ways of
doing this, as described in <a href="#Unicode-and-UTF-8">Unicode and UTF-8</a>.</p>
<p>The current locale is set at execution time by
<a href="#The-setlocale-function">setlocale()</a> described below.  If that function
hasn't yet been called in the course of the program's execution, the
current locale is that which was determined by the <a href="#ENVIRONMENT">ENVIRONMENT</a> in
effect at the start of the program, except that
<code class="inline"><a href="#Category-LC_NUMERIC%3a-Numeric-Formatting">LC_NUMERIC</a></code> is always
initialized to the C locale (mentioned under <a href="#Finding-locales">Finding locales</a>).
If there is no valid environment, the current locale is undefined.  It
is likely, but not necessarily, the "C" locale.</p>
<p>The operations that are affected by locale are:</p>
<ul>
<li><a name="*Under-use-locale-'%3anot_characters'%3b*"></a><b><b>Under <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span><span class="sc">;</span></code>
</b></b>
<ul>
<li>
<p><b>Format declarations</b> (format()) use <code class="inline"><span class="w">LC_NUMERIC</span></code>
</p>
</li>
<li>
<p><b>The POSIX date formatting function</b> (strftime()) uses <code class="inline"><span class="w">LC_TIME</span></code>
.</p>
</li>
</ul>
<p>&#xa0;</p>
</li>
<li><a name="*Under-just-plain-use-locale%3b*"></a><b><b>Under just plain <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span><span class="sc">;</span></code>
</b></b>
<p>The above operations are affected, as well as the following:</p>
<ul>
<li>
<p><b>The comparison operators</b> (<code class="inline">lt</code>
, <code class="inline">le</code>
, <code class="inline">cmp</code>
, <code class="inline">ge</code>
, and <code class="inline">gt</code>
) and
the POSIX string collation functions strcoll() and strxfrm() use
<code class="inline"><span class="w">LC_COLLATE</span></code>
.  sort() is also affected if used without an
explicit comparison function, because it uses <code class="inline">cmp</code>
 by default.</p>
<p><b>Note:</b> <code class="inline">eq</code>
 and <code class="inline">ne</code>
 are unaffected by locale: they always
perform a char-by-char comparison of their scalar operands.  What's
more, if <code class="inline">cmp</code>
 finds that its operands are equal according to the
collation sequence specified by the current locale, it goes on to
perform a char-by-char comparison, and only returns <i>0</i> (equal) if the
operands are char-for-char identical.  If you really want to know whether
two strings--which <code class="inline">eq</code>
 and <code class="inline">cmp</code>
 may consider different--are equal
as far as collation in the locale is concerned, see the discussion in
<a href="#Category-LC_COLLATE%3a-Collation">Category LC_COLLATE: Collation</a>.</p>
</li>
<li>
<p><b>Regular expressions and case-modification functions</b> (uc(), lc(),
ucfirst(), and lcfirst()) use <code class="inline"><span class="w">LC_CTYPE</span></code>
</p>
</li>
</ul>
</li>
</ul>
<p>The default behavior is restored with the <code class="inline"><a class="l_k" href="functions/no.html">no</a> <span class="w">locale</span></code>
 pragma, or
upon reaching the end of the block enclosing <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
.
Note that <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 and <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
 may be
nested, and that what is in effect within an inner scope will revert to
the outer scope's rules at the end of the inner scope.</p>
<p>The string result of any operation that uses locale
information is tainted, as it is possible for a locale to be
untrustworthy.  See <a href="#SECURITY">SECURITY</a>.</p>
<a name="The-setlocale-function"></a><h2>The setlocale function</h2>
<p>You can switch locales as often as you wish at run time with the
POSIX::setlocale() function:</p>
<pre class="verbatim"><ol><li>        <span class="c"># Import locale-handling tool set from POSIX module.</span></li><li>        <span class="c"># This example uses: setlocale -- the function call</span></li><li>        <span class="c">#                    LC_CTYPE -- explained below</span></li><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(locale_h)</span><span class="sc">;</span></li><li></li><li>        <span class="c"># query and save the old locale</span></li><li>        <span class="i">$old_locale</span> = <span class="i">setlocale</span><span class="s">(</span><span class="w">LC_CTYPE</span><span class="s">)</span><span class="sc">;</span></li><li></li><li>        <span class="i">setlocale</span><span class="s">(</span><span class="w">LC_CTYPE</span><span class="cm">,</span> <span class="q">&quot;fr_CA.ISO8859-1&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>        <span class="c"># LC_CTYPE now in locale &quot;French, Canada, codeset ISO 8859-1&quot;</span></li><li></li><li>        <span class="i">setlocale</span><span class="s">(</span><span class="w">LC_CTYPE</span><span class="cm">,</span> <span class="q">&quot;&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>        <span class="c"># LC_CTYPE now reset to default defined by LC_ALL/LC_CTYPE/LANG</span></li><li>        <span class="c"># environment variables.  See below for documentation.</span></li><li></li><li>        <span class="c"># restore the old locale</span></li><li>        <span class="i">setlocale</span><span class="s">(</span><span class="w">LC_CTYPE</span><span class="cm">,</span> <span class="i">$old_locale</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The first argument of setlocale() gives the <b>category</b>, the second the
<b>locale</b>.  The category tells in what aspect of data processing you
want to apply locale-specific rules.  Category names are discussed in
<a href="#LOCALE-CATEGORIES">LOCALE CATEGORIES</a> and <a href="#ENVIRONMENT">ENVIRONMENT</a>.  The locale is the name of a
collection of customization information corresponding to a particular
combination of language, country or territory, and codeset.  Read on for
hints on the naming of locales: not all systems name locales as in the
example.</p>
<p>If no second argument is provided and the category is something else
than LC_ALL, the function returns a string naming the current locale
for the category.  You can use this value as the second argument in a
subsequent call to setlocale().</p>
<p>If no second argument is provided and the category is LC_ALL, the
result is implementation-dependent.  It may be a string of
concatenated locale names (separator also implementation-dependent)
or a single locale name.  Please consult your setlocale(3) man page for
details.</p>
<p>If a second argument is given and it corresponds to a valid locale,
the locale for the category is set to that value, and the function
returns the now-current locale value.  You can then use this in yet
another call to setlocale().  (In some implementations, the return
value may sometimes differ from the value you gave as the second
argument--think of it as an alias for the value you gave.)</p>
<p>As the example shows, if the second argument is an empty string, the
category's locale is returned to the default specified by the
corresponding environment variables.  Generally, this results in a
return to the default that was in force when Perl started up: changes
to the environment made by the application after startup may or may not
be noticed, depending on your system's C library.</p>
<p>If the second argument does not correspond to a valid locale, the locale
for the category is not changed, and the function returns <i>undef</i>.</p>
<p>Note that Perl ignores the current <code class="inline"><span class="w">LC_CTYPE</span></code>
 and <code class="inline"><span class="w">LC_COLLATE</span></code>
 locales
within the scope of a <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
.</p>
<p>For further information about the categories, consult setlocale(3).</p>
<a name="Finding-locales"></a><h2>Finding locales</h2>
<p>For locales available in your system, consult also setlocale(3) to
see whether it leads to the list of available locales (search for the
<i>SEE ALSO</i> section).  If that fails, try the following command lines:</p>
<pre class="verbatim"><ol><li>        <span class="w">locale</span> -<span class="w">a</span></li><li></li><li>        <span class="w">nlsinfo</span></li><li></li><li>        <span class="w">ls</span> /<span class="w">usr</span>/<span class="w">lib</span>/<span class="w">nls</span>/<span class="w">loc</span></li><li></li><li>        <span class="w">ls</span> /<span class="w">usr</span>/<span class="w">lib</span>/<span class="w">locale</span></li><li></li><li>        <span class="w">ls</span> /<span class="w">usr</span>/<span class="w">lib</span>/<span class="w">nls</span></li><li></li><li>	<span class="w">ls</span> /<span class="w">usr</span>/<span class="w">share</span>/<span class="w">locale</span></li></ol></pre><p>and see whether they list something resembling these</p>
<pre class="verbatim"><ol><li>        en_US.ISO8859-1     de_DE.ISO8859-1     ru_RU.ISO8859-5</li><li>        en_US.iso88591      de_DE.iso88591      ru_RU.iso88595</li><li>        en_US               de_DE               ru_RU</li><li>        en                  de                  ru</li><li>        english             german              russian</li><li>        english.iso88591    german.iso88591     russian.iso88595</li><li>        english.roman8                          russian.koi8r</li></ol></pre><p>Sadly, even though the calling interface for setlocale() has been
standardized, names of locales and the directories where the
configuration resides have not been.  The basic form of the name is
<i>language_territory</i><b>.</b><i>codeset</i>, but the latter parts after
<i>language</i> are not always present.  The <i>language</i> and <i>country</i>
are usually from the standards <b>ISO 3166</b> and <b>ISO 639</b>, the
two-letter abbreviations for the countries and the languages of the
world, respectively.  The <i>codeset</i> part often mentions some <b>ISO
8859</b> character set, the Latin codesets.  For example, <code class="inline"><span class="w">ISO</span> <span class="n">8859</span>-<span class="n">1</span></code>

is the so-called "Western European codeset" that can be used to encode
most Western European languages adequately.  Again, there are several
ways to write even the name of that one standard.  Lamentably.</p>
<p>Two special locales are worth particular mention: "C" and "POSIX".
Currently these are effectively the same locale: the difference is
mainly that the first one is defined by the C standard, the second by
the POSIX standard.  They define the <b>default locale</b> in which
every program starts in the absence of locale information in its
environment.  (The <i>default</i> default locale, if you will.)  Its language
is (American) English and its character codeset ASCII.
<b>Warning</b>. The C locale delivered by some vendors may not
actually exactly match what the C standard calls for.  So beware.</p>
<p><b>NOTE</b>: Not all systems have the "POSIX" locale (not all systems are
POSIX-conformant), so use "C" when you need explicitly to specify this
default locale.</p>
<a name="LOCALE-PROBLEMS"></a><h2>LOCALE PROBLEMS</h2>
<p>You may encounter the following warning message at Perl startup:</p>
<pre class="verbatim"><ol><li>	perl: warning: Setting locale failed.</li><li>	perl: warning: Please check that your locale settings:</li><li>	        LC_ALL = "En_US",</li><li>	        LANG = (unset)</li><li>	    are supported and installed on your system.</li><li>	perl: warning: Falling back to the standard locale ("C").</li></ol></pre><p>This means that your locale settings had LC_ALL set to "En_US" and
LANG exists but has no value.  Perl tried to believe you but could not.
Instead, Perl gave up and fell back to the "C" locale, the default locale
that is supposed to work no matter what.  This usually means your locale
settings were wrong, they mention locales your system has never heard
of, or the locale installation in your system has problems (for example,
some system files are broken or missing).  There are quick and temporary
fixes to these problems, as well as more thorough and lasting fixes.</p>
<a name="Temporarily-fixing-locale-problems"></a><h2>Temporarily fixing locale problems</h2>
<p>The two quickest fixes are either to render Perl silent about any
locale inconsistencies or to run Perl under the default locale "C".</p>
<p>Perl's moaning about locale problems can be silenced by setting the
environment variable PERL_BADLANG to a zero value, for example "0".
This method really just sweeps the problem under the carpet: you tell
Perl to shut up even when Perl sees that something is wrong.  Do not
be surprised if later something locale-dependent misbehaves.</p>
<p>Perl can be run under the "C" locale by setting the environment
variable LC_ALL to "C".  This method is perhaps a bit more civilized
than the PERL_BADLANG approach, but setting LC_ALL (or
other locale variables) may affect other programs as well, not just
Perl.  In particular, external programs run from within Perl will see
these changes.  If you make the new settings permanent (read on), all
programs you run see the changes.  See <a href="#ENVIRONMENT">ENVIRONMENT</a> for
the full list of relevant environment variables and <a href="#USING-LOCALES">USING LOCALES</a>
for their effects in Perl.  Effects in other programs are
easily deducible.  For example, the variable LC_COLLATE may well affect
your <b>sort</b> program (or whatever the program that arranges "records"
alphabetically in your system is called).</p>
<p>You can test out changing these variables temporarily, and if the
new settings seem to help, put those settings into your shell startup
files.  Consult your local documentation for the exact details.  For in
Bourne-like shells (<b>sh</b>, <b>ksh</b>, <b>bash</b>, <b>zsh</b>):</p>
<pre class="verbatim"><ol><li>	LC_ALL=en_US.ISO8859-1</li><li>	export LC_ALL</li></ol></pre><p>This assumes that we saw the locale "en_US.ISO8859-1" using the commands
discussed above.  We decided to try that instead of the above faulty
locale "En_US"--and in Cshish shells (<b>csh</b>, <b>tcsh</b>)</p>
<pre class="verbatim"><ol><li>	<span class="w">setenv</span> <span class="w">LC_ALL</span> <span class="w">en_US</span>.<span class="w">ISO8859</span>-<span class="n">1</span></li></ol></pre><p>or if you have the "env" application you can do in any shell</p>
<pre class="verbatim"><ol><li>	env LC_ALL=en_US.ISO8859-1 perl ...</li></ol></pre><p>If you do not know what shell you have, consult your local
helpdesk or the equivalent.</p>
<a name="Permanently-fixing-locale-problems"></a><h2>Permanently fixing locale problems</h2>
<p>The slower but superior fixes are when you may be able to yourself
fix the misconfiguration of your own environment variables.  The
mis(sing)configuration of the whole system's locales usually requires
the help of your friendly system administrator.</p>
<p>First, see earlier in this document about <a href="#Finding-locales">Finding locales</a>.  That tells
how to find which locales are really supported--and more importantly,
installed--on your system.  In our example error message, environment
variables affecting the locale are listed in the order of decreasing
importance (and unset variables do not matter).  Therefore, having
LC_ALL set to "En_US" must have been the bad choice, as shown by the
error message.  First try fixing locale settings listed first.</p>
<p>Second, if using the listed commands you see something <b>exactly</b>
(prefix matches do not count and case usually counts) like "En_US"
without the quotes, then you should be okay because you are using a
locale name that should be installed and available in your system.
In this case, see <a href="#Permanently-fixing-your-system's-locale-configuration">Permanently fixing your system's locale configuration</a>.</p>
<a name="Permanently-fixing-your-system's-locale-configuration"></a><h2>Permanently fixing your system's locale configuration</h2>
<p>This is when you see something like:</p>
<pre class="verbatim"><ol><li>	perl: warning: Please check that your locale settings:</li><li>	        LC_ALL = "En_US",</li><li>	        LANG = (unset)</li><li>	    are supported and installed on your system.</li></ol></pre><p>but then cannot see that "En_US" listed by the above-mentioned
commands.  You may see things like "en_US.ISO8859-1", but that isn't
the same.  In this case, try running under a locale
that you can list and which somehow matches what you tried.  The
rules for matching locale names are a bit vague because
standardization is weak in this area.  See again the
<a href="#Finding-locales">Finding locales</a> about general rules.</p>
<a name="Fixing-system-locale-configuration"></a><h2>Fixing system locale configuration</h2>
<p>Contact a system administrator (preferably your own) and report the exact
error message you get, and ask them to read this same documentation you
are now reading.  They should be able to check whether there is something
wrong with the locale configuration of the system.  The <a href="#Finding-locales">Finding locales</a>
section is unfortunately a bit vague about the exact commands and places
because these things are not that standardized.</p>
<a name="The-localeconv-function"></a><h2>The localeconv function</h2>
<p>The POSIX::localeconv() function allows you to get particulars of the
locale-dependent numeric formatting information specified by the current
<code class="inline"><span class="w">LC_NUMERIC</span></code>
 and <code class="inline"><span class="w">LC_MONETARY</span></code>
 locales.  (If you just want the name of
the current locale for a particular category, use POSIX::setlocale()
with a single parameter--see <a href="#The-setlocale-function">The setlocale function</a>.)</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(locale_h)</span><span class="sc">;</span></li><li></li><li>        <span class="c"># Get a reference to a hash of locale-dependent info</span></li><li>        <span class="i">$locale_values</span> = <span class="i">localeconv</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li><li></li><li>        <span class="c"># Output sorted list of the values</span></li><li>        for <span class="s">(</span><a class="l_k" href="functions/sort.html">sort</a> <a class="l_k" href="functions/keys.html">keys</a> <span class="i">%$locale_values</span><span class="s">)</span> <span class="s">{</span></li><li>            <a class="l_k" href="functions/printf.html">printf</a> <span class="q">&quot;%-20s = %s\n&quot;</span><span class="cm">,</span> <span class="i">$_</span><span class="cm">,</span> <span class="i">$locale_values</span>-&gt;{<span class="i">$_</span>}</li><li>        <span class="s">}</span></li></ol></pre><p>localeconv() takes no arguments, and returns <b>a reference to</b> a hash.
The keys of this hash are variable names for formatting, such as
<code class="inline"><span class="w">decimal_point</span></code>
 and <code class="inline"><span class="w">thousands_sep</span></code>
.  The values are the
corresponding, er, values.  See <a href="POSIX.html#localeconv">localeconv in POSIX</a> for a longer
example listing the categories an implementation might be expected to
provide; some provide more and others fewer.  You don't need an
explicit <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
, because localeconv() always observes the
current locale.</p>
<p>Here's a simple-minded example program that rewrites its command-line
parameters as integers correctly formatted in the current locale:</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(locale_h)</span><span class="sc">;</span></li><li></li><li>    <span class="c"># Get some of locale&#39;s numeric formatting parameters</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="s">(</span><span class="i">$thousands_sep</span><span class="cm">,</span> <span class="i">$grouping</span><span class="s">)</span> =</li><li>            <span class="i">@</span>{<span class="i">localeconv</span><span class="s">(</span><span class="s">)</span>}{<span class="q">&#39;thousands_sep&#39;</span><span class="cm">,</span> <span class="q">&#39;grouping&#39;</span>}<span class="sc">;</span></li><li></li><li>    <span class="c"># Apply defaults if values are missing</span></li><li>    <span class="i">$thousands_sep</span> = <span class="q">&#39;,&#39;</span> <a class="l_k" href="functions/unless.html">unless</a> <span class="i">$thousands_sep</span><span class="sc">;</span></li><li></li><li>    <span class="c"># grouping and mon_grouping are packed lists</span></li><li>    <span class="c"># of small integers (characters) telling the</span></li><li>    <span class="c"># grouping (thousand_seps and mon_thousand_seps</span></li><li>    <span class="c"># being the group dividers) of numbers and</span></li><li>    <span class="c"># monetary quantities.  The integers&#39; meanings:</span></li><li>    <span class="c"># 255 means no more grouping, 0 means repeat</span></li><li>    <span class="c"># the previous grouping, 1-254 means use that</span></li><li>    <span class="c"># as the current grouping.  Grouping goes from</span></li><li>    <span class="c"># right to left (low to high digits).  In the</span></li><li>    <span class="c"># below we cheat slightly by never using anything</span></li><li>    <span class="c"># else than the first grouping (whatever that is).</span></li><li>    <a class="l_k" href="functions/if.html">if</a> <span class="s">(</span><span class="i">$grouping</span><span class="s">)</span> <span class="s">{</span></li><li>        <span class="i">@grouping</span> = <a class="l_k" href="functions/unpack.html">unpack</a><span class="s">(</span><span class="q">&quot;C*&quot;</span><span class="cm">,</span> <span class="i">$grouping</span><span class="s">)</span><span class="sc">;</span></li><li>    <span class="s">}</span> <a class="l_k" href="functions/else.html">else</a> <span class="s">{</span></li><li>        <span class="i">@grouping</span> = <span class="s">(</span><span class="n">3</span><span class="s">)</span><span class="sc">;</span></li><li>    <span class="s">}</span></li><li></li><li>    <span class="c"># Format command line params for current locale</span></li><li>    <a class="l_k" href="functions/for.html">for</a> <span class="s">(</span><span class="i">@ARGV</span><span class="s">)</span> <span class="s">{</span></li><li>        <span class="i">$_</span> = <a class="l_k" href="functions/int.html">int</a><span class="sc">;</span>    <span class="c"># Chop non-integer part</span></li><li>        <span class="n">1</span> <a class="l_k" href="functions/while.html">while</a></li><li>        <span class="q">s/(\d)(\d{$grouping[0]}($|$thousands_sep))/$1$thousands_sep$2/</span><span class="sc">;</span></li><li>        <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;$_&quot;</span><span class="sc">;</span></li><li>    <span class="s">}</span></li><li>    <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;\n&quot;</span><span class="sc">;</span></li></ol></pre><a name="I18N%3a%3aLanginfo"></a><h2>I18N::Langinfo</h2>
<p>Another interface for querying locale-dependent information is the
I18N::Langinfo::langinfo() function, available at least in Unix-like
systems and VMS.</p>
<p>The following example will import the langinfo() function itself and
three constants to be used as arguments to langinfo(): a constant for
the abbreviated first day of the week (the numbering starts from
Sunday = 1) and two more constants for the affirmative and negative
answers for a yes/no question in the current locale.</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">I18N::Langinfo</span> <span class="q">qw(langinfo ABDAY_1 YESSTR NOSTR)</span><span class="sc">;</span></li><li></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="s">(</span><span class="i">$abday_1</span><span class="cm">,</span> <span class="i">$yesstr</span><span class="cm">,</span> <span class="i">$nostr</span><span class="s">)</span></li><li>                = <a class="l_k" href="functions/map.html">map</a> <span class="s">{</span> <span class="w">langinfo</span> <span class="s">}</span> <span class="q">qw(ABDAY_1 YESSTR NOSTR)</span><span class="sc">;</span></li><li></li><li>    <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;$abday_1? [$yesstr/$nostr] &quot;</span><span class="sc">;</span></li></ol></pre><p>In other words, in the "C" (or English) locale the above will probably
print something like:</p>
<pre class="verbatim"><ol><li>    Sun? [yes/no]</li></ol></pre><p>See <a href="I18N/Langinfo.html">I18N::Langinfo</a> for more information.</p>
<a name="LOCALE-CATEGORIES"></a><h1>LOCALE CATEGORIES</h1>
<p>The following subsections describe basic locale categories.  Beyond these,
some combination categories allow manipulation of more than one
basic category at a time.  See <a href="#ENVIRONMENT">ENVIRONMENT</a> for a discussion of these.</p>
<a name="Category-LC_COLLATE%3a-Collation"></a><h2>Category LC_COLLATE: Collation</h2>
<p>In the scope of <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 (but not a
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
), Perl looks to the <code class="inline"><span class="w">LC_COLLATE</span></code>

environment variable to determine the application's notions on collation
(ordering) of characters.  For example, "b" follows "a" in Latin
alphabets, but where do "&#xe1;" and "&#xe5;" belong?  And while
"color" follows "chocolate" in English, what about in traditional Spanish?</p>
<p>The following collations all make sense and you may meet any of them
if you "use locale".</p>
<pre class="verbatim"><ol><li>	<span class="w">A</span> <span class="w">B</span> <span class="w">C</span> <span class="w">D</span> <span class="w">E</span> <span class="w">a</span> <span class="w">b</span> <span class="w">c</span> <span class="w">d</span> <span class="w">e</span></li><li>	<span class="w">A</span> <span class="w">a</span> <span class="w">B</span> <span class="w">b</span> <span class="w">C</span> <span class="w">c</span> <span class="w">D</span> <span class="w">d</span> <span class="w">E</span> <span class="w">e</span></li><li>	<span class="w">a</span> <span class="w">A</span> <span class="w">b</span> <span class="w">B</span> <span class="w">c</span> <span class="w">C</span> <span class="w">d</span> <span class="w">D</span> <span class="w">e</span> <span class="w">E</span></li><li>	<span class="w">a</span> <span class="w">b</span> <span class="w">c</span> <span class="w">d</span> <span class="w">e</span> <span class="w">A</span> <span class="w">B</span> <span class="w">C</span> <span class="w">D</span> <span class="w">E</span></li></ol></pre><p>Here is a code snippet to tell what "word"
characters are in the current locale, in that locale's order:</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span><span class="sc">;</span></li><li>        <a class="l_k" href="functions/print.html">print</a> +<span class="s">(</span><a class="l_k" href="functions/sort.html">sort</a> <a class="l_k" href="functions/grep.html">grep</a> <span class="q">/\w/</span><span class="cm">,</span> <a class="l_k" href="functions/map.html">map</a> <span class="s">{</span> <a class="l_k" href="functions/chr.html">chr</a> <span class="s">}</span> <span class="n">0</span>..<span class="n">255</span><span class="s">)</span><span class="cm">,</span> <span class="q">&quot;\n&quot;</span><span class="sc">;</span></li></ol></pre><p>Compare this with the characters that you see and their order if you
state explicitly that the locale should be ignored:</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/no.html">no</a> <span class="w">locale</span><span class="sc">;</span></li><li>        <a class="l_k" href="functions/print.html">print</a> +<span class="s">(</span><a class="l_k" href="functions/sort.html">sort</a> <a class="l_k" href="functions/grep.html">grep</a> <span class="q">/\w/</span><span class="cm">,</span> <a class="l_k" href="functions/map.html">map</a> <span class="s">{</span> <a class="l_k" href="functions/chr.html">chr</a> <span class="s">}</span> <span class="n">0</span>..<span class="n">255</span><span class="s">)</span><span class="cm">,</span> <span class="q">&quot;\n&quot;</span><span class="sc">;</span></li></ol></pre><p>This machine-native collation (which is what you get unless <code class="inline"><a class="l_k" href="functions/use.html">use</a>
<span class="w">locale</span></code>
 has appeared earlier in the same block) must be used for
sorting raw binary data, whereas the locale-dependent collation of the
first example is useful for natural text.</p>
<p>As noted in <a href="#USING-LOCALES">USING LOCALES</a>, <code class="inline">cmp</code>
 compares according to the current
collation locale when <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 is in effect, but falls back to a
char-by-char comparison for strings that the locale says are equal. You
can use POSIX::strcoll() if you don't want this fall-back:</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(strcoll)</span><span class="sc">;</span></li><li>        <span class="i">$equal_in_locale</span> =</li><li>            !<span class="i">strcoll</span><span class="s">(</span><span class="q">&quot;space and case ignored&quot;</span><span class="cm">,</span> <span class="q">&quot;SpaceAndCaseIgnored&quot;</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>$equal_in_locale will be true if the collation locale specifies a
dictionary-like ordering that ignores space characters completely and
which folds case.</p>
<p>If you have a single string that you want to check for "equality in
locale" against several others, you might think you could gain a little
efficiency by using POSIX::strxfrm() in conjunction with <code class="inline">eq</code>
:</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(strxfrm)</span><span class="sc">;</span></li><li>        <span class="i">$xfrm_string</span> = <span class="i">strxfrm</span><span class="s">(</span><span class="q">&quot;Mixed-case string&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>        <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;locale collation ignores spaces\n&quot;</span></li><li>            if <span class="i">$xfrm_string</span> eq <span class="i">strxfrm</span><span class="s">(</span><span class="q">&quot;Mixed-casestring&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>        <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;locale collation ignores hyphens\n&quot;</span></li><li>            if <span class="i">$xfrm_string</span> eq <span class="i">strxfrm</span><span class="s">(</span><span class="q">&quot;Mixedcase string&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>        <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;locale collation ignores case\n&quot;</span></li><li>            if <span class="i">$xfrm_string</span> eq <span class="i">strxfrm</span><span class="s">(</span><span class="q">&quot;mixed-case string&quot;</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>strxfrm() takes a string and maps it into a transformed string for use
in char-by-char comparisons against other transformed strings during
collation.  "Under the hood", locale-affected Perl comparison operators
call strxfrm() for both operands, then do a char-by-char
comparison of the transformed strings.  By calling strxfrm() explicitly
and using a non locale-affected comparison, the example attempts to save
a couple of transformations.  But in fact, it doesn't save anything: Perl
magic (see <a href="perlguts.html#Magic-Variables">Magic Variables in perlguts</a>) creates the transformed version of a
string the first time it's needed in a comparison, then keeps this version around
in case it's needed again.  An example rewritten the easy way with
<code class="inline">cmp</code>
 runs just about as fast.  It also copes with null characters
embedded in strings; if you call strxfrm() directly, it treats the first
null it finds as a terminator.  don't expect the transformed strings
it produces to be portable across systems--or even from one revision
of your operating system to the next.  In short, don't call strxfrm()
directly: let Perl do it for you.</p>
<p>Note: <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 isn't shown in some of these examples because it isn't
needed: strcoll() and strxfrm() exist only to generate locale-dependent
results, and so always obey the current <code class="inline"><span class="w">LC_COLLATE</span></code>
 locale.</p>
<a name="Category-LC_CTYPE%3a-Character-Types"></a><h2>Category LC_CTYPE: Character Types</h2>
<p>In the scope of <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 (but not a
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
), Perl obeys the <code class="inline"><span class="w">LC_CTYPE</span></code>
 locale
setting.  This controls the application's notion of which characters are
alphabetic.  This affects Perl's <code class="inline">\<span class="w">w</span></code>
 regular expression metanotation,
which stands for alphanumeric characters--that is, alphabetic,
numeric, and including other special characters such as the underscore or
hyphen.  (Consult <a href="perlre.html">perlre</a> for more information about
regular expressions.)  Thanks to <code class="inline"><span class="w">LC_CTYPE</span></code>
, depending on your locale
setting, characters like "&#xe6;", "&#xf0;", "&#xdf;", and
"&#xf8;" may be understood as <code class="inline">\<span class="w">w</span></code>
 characters.</p>
<p>The <code class="inline"><span class="w">LC_CTYPE</span></code>
 locale also provides the map used in transliterating
characters between lower and uppercase.  This affects the case-mapping
functions--lc(), lcfirst, uc(), and ucfirst(); case-mapping
interpolation with <code class="inline">\<span class="w">l</span></code>
, <code class="inline">\<span class="w">L</span></code>
, <code class="inline">\<span class="w">u</span></code>
, or <code class="inline">\<span class="w">U</span></code>
 in double-quoted strings
and <code class="inline"><a class="l_k" href="functions/s.html">s///</a></code> substitutions; and case-independent regular expression
pattern matching using the <code class="inline"><span class="w">i</span></code>
 modifier.</p>
<p>Finally, <code class="inline"><span class="w">LC_CTYPE</span></code>
 affects the POSIX character-class test
functions--isalpha(), islower(), and so on.  For example, if you move
from the "C" locale to a 7-bit Scandinavian one, you may find--possibly
to your surprise--that "|" moves from the ispunct() class to isalpha().
Unfortunately, this creates big problems for regular expressions. "|" still
means alternation even though it matches <code class="inline">\<span class="w">w</span></code>
.</p>
<p>Note that there are quite a few things that are unaffected by the
current locale.  All the escape sequences for particular characters,
<code class="inline">\<span class="w">n</span></code>
 for example, always mean the platform's native one.  This means,
for example, that <code class="inline">\<span class="w">N</span></code>
 in regular expressions (every character
but new-line) work on the platform character set.</p>
<p><b>Note:</b> A broken or malicious <code class="inline"><span class="w">LC_CTYPE</span></code>
 locale definition may result
in clearly ineligible characters being considered to be alphanumeric by
your application.  For strict matching of (mundane) ASCII letters and
digits--for example, in command strings--locale-aware applications
should use <code class="inline">\<span class="w">w</span></code>
 with the <code class="inline"><span class="q">/a</span></code>
 regular expression modifier.  See <a href="#SECURITY">SECURITY</a>.</p>
<a name="Category-LC_NUMERIC%3a-Numeric-Formatting"></a><h2>Category LC_NUMERIC: Numeric Formatting</h2>
<p>After a proper POSIX::setlocale() call, Perl obeys the <code class="inline"><span class="w">LC_NUMERIC</span></code>

locale information, which controls an application's idea of how numbers
should be formatted for human readability by the printf(), sprintf(), and
write() functions. String-to-numeric conversion by the POSIX::strtod()
function is also affected.  In most implementations the only effect is to
change the character used for the decimal point--perhaps from "."  to ",".
These functions aren't aware of such niceties as thousands separation and
so on. (See <a href="#The-localeconv-function">The localeconv function</a> if you care about these things.)</p>
<p>Output produced by print() is also affected by the current locale: it
corresponds to what you'd get from printf() in the "C" locale.  The
same is true for Perl's internal conversions between numeric and
string formats:</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(strtod setlocale LC_NUMERIC)</span><span class="sc">;</span></li><li></li><li>	<span class="w">setlocale</span> <span class="w">LC_NUMERIC</span><span class="cm">,</span> <span class="q">&quot;&quot;</span><span class="sc">;</span></li><li></li><li>        <span class="i">$n</span> = <span class="n">5</span>/<span class="n">2</span><span class="sc">;</span>   <span class="c"># Assign numeric 2.5 to $n</span></li><li></li><li>        <span class="i">$a</span> = <span class="q">&quot; $n&quot;</span><span class="sc">;</span> <span class="c"># Locale-dependent conversion to string</span></li><li></li><li>        <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;half five is $n\n&quot;</span><span class="sc">;</span>       <span class="c"># Locale-dependent output</span></li><li></li><li>        <a class="l_k" href="functions/printf.html">printf</a> <span class="q">&quot;half five is %g\n&quot;</span><span class="cm">,</span> <span class="i">$n</span><span class="sc">;</span>  <span class="c"># Locale-dependent output</span></li><li></li><li>        <a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;DECIMAL POINT IS COMMA\n&quot;</span></li><li>            if <span class="i">$n</span> == <span class="s">(</span><span class="i">strtod</span><span class="s">(</span><span class="q">&quot;2,5&quot;</span><span class="s">)</span><span class="s">)</span>[<span class="n">0</span>]<span class="sc">;</span> <span class="c"># Locale-dependent conversion</span></li></ol></pre><p>See also <a href="I18N/Langinfo.html">I18N::Langinfo</a> and <code class="inline"><span class="w">RADIXCHAR</span></code>
.</p>
<a name="Category-LC_MONETARY%3a-Formatting-of-monetary-amounts"></a><h2>Category LC_MONETARY: Formatting of monetary amounts</h2>
<p>The C standard defines the <code class="inline"><span class="w">LC_MONETARY</span></code>
 category, but not a function
that is affected by its contents.  (Those with experience of standards
committees will recognize that the working group decided to punt on the
issue.)  Consequently, Perl takes no notice of it.  If you really want
to use <code class="inline"><span class="w">LC_MONETARY</span></code>
, you can query its contents--see
<a href="#The-localeconv-function">The localeconv function</a>--and use the information that it returns in your
application's own formatting of currency amounts.  However, you may well
find that the information, voluminous and complex though it may be, still
does not quite meet your requirements: currency formatting is a hard nut
to crack.</p>
<p>See also <a href="I18N/Langinfo.html">I18N::Langinfo</a> and <code class="inline"><span class="w">CRNCYSTR</span></code>
.</p>
<a name="LC_TIME"></a><h2>LC_TIME</h2>
<p>Output produced by POSIX::strftime(), which builds a formatted
human-readable date/time string, is affected by the current <code class="inline"><span class="w">LC_TIME</span></code>

locale.  Thus, in a French locale, the output produced by the <code class="inline"><span class="i">%B</span></code>

format element (full month name) for the first month of the year would
be "janvier".  Here's how to get a list of long month names in the
current locale:</p>
<pre class="verbatim"><ol><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(strftime)</span><span class="sc">;</span></li><li>        for <span class="s">(</span><span class="n">0</span>..<span class="n">11</span><span class="s">)</span> <span class="s">{</span></li><li>            <span class="i">$long_month_name</span>[<span class="i">$_</span>] =</li><li>                <span class="i">strftime</span><span class="s">(</span><span class="q">&quot;%B&quot;</span><span class="cm">,</span> <span class="n">0</span><span class="cm">,</span> <span class="n">0</span><span class="cm">,</span> <span class="n">0</span><span class="cm">,</span> <span class="n">1</span><span class="cm">,</span> <span class="i">$_</span><span class="cm">,</span> <span class="n">96</span><span class="s">)</span><span class="sc">;</span></li><li>        <span class="s">}</span></li></ol></pre><p>Note: <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 isn't needed in this example: as a function that
exists only to generate locale-dependent results, strftime() always
obeys the current <code class="inline"><span class="w">LC_TIME</span></code>
 locale.</p>
<p>See also <a href="I18N/Langinfo.html">I18N::Langinfo</a> and <code class="inline"><span class="w">ABDAY_1</span></code>
..<code class="inline"><span class="w">ABDAY_7</span></code>
, <code class="inline"><span class="w">DAY_1</span></code>
..<code class="inline"><span class="w">DAY_7</span></code>
,
<code class="inline"><span class="w">ABMON_1</span></code>
..<code class="inline"><span class="w">ABMON_12</span></code>
, and <code class="inline"><span class="w">ABMON_1</span></code>
..<code class="inline"><span class="w">ABMON_12</span></code>
.</p>
<a name="Other-categories"></a><h2>Other categories</h2>
<p>The remaining locale category, <code class="inline"><span class="w">LC_MESSAGES</span></code>
 (possibly supplemented
by others in particular implementations) is not currently used by
Perl--except possibly to affect the behavior of library functions
called by extensions outside the standard Perl distribution and by the
operating system and its utilities.  Note especially that the string
value of <code class="inline"><span class="i">$!</span></code>
 and the error messages given by external utilities may
be changed by <code class="inline"><span class="w">LC_MESSAGES</span></code>
.  If you want to have portable error
codes, use <code class="inline"><span class="i">%!</span></code>
.  See <a href="Errno.html">Errno</a>.</p>
<a name="SECURITY"></a><h1>SECURITY</h1>
<p>Although the main discussion of Perl security issues can be found in
<a href="perlsec.html">perlsec</a>, a discussion of Perl's locale handling would be incomplete
if it did not draw your attention to locale-dependent security issues.
Locales--particularly on systems that allow unprivileged users to
build their own locales--are untrustworthy.  A malicious (or just plain
broken) locale can make a locale-aware application give unexpected
results.  Here are a few possibilities:</p>
<ul>
<li>
<p>Regular expression checks for safe file names or mail addresses using
<code class="inline">\<span class="w">w</span></code>
 may be spoofed by an <code class="inline"><span class="w">LC_CTYPE</span></code>
 locale that claims that
characters such as "&gt;" and "|" are alphanumeric.</p>
</li>
<li>
<p>String interpolation with case-mapping, as in, say, <code class="inline"><span class="i">$dest</span> =
<span class="q">&quot;C:\U$name.$ext&quot;</span></code>
, may produce dangerous results if a bogus LC_CTYPE
case-mapping table is in effect.</p>
</li>
<li>
<p>A sneaky <code class="inline"><span class="w">LC_COLLATE</span></code>
 locale could result in the names of students with
"D" grades appearing ahead of those with "A"s.</p>
</li>
<li>
<p>An application that takes the trouble to use information in
<code class="inline"><span class="w">LC_MONETARY</span></code>
 may format debits as if they were credits and vice versa
if that locale has been subverted.  Or it might make payments in US
dollars instead of Hong Kong dollars.</p>
</li>
<li>
<p>The date and day names in dates formatted by strftime() could be
manipulated to advantage by a malicious user able to subvert the
<code class="inline"><span class="w">LC_DATE</span></code>
 locale.  ("Look--it says I wasn't in the building on
Sunday.")</p>
</li>
</ul>
<p>Such dangers are not peculiar to the locale system: any aspect of an
application's environment which may be modified maliciously presents
similar challenges.  Similarly, they are not specific to Perl: any
programming language that allows you to write programs that take
account of their environment exposes you to these issues.</p>
<p>Perl cannot protect you from all possibilities shown in the
examples--there is no substitute for your own vigilance--but, when
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 is in effect, Perl uses the tainting mechanism (see
<a href="perlsec.html">perlsec</a>) to mark string results that become locale-dependent, and
which may be untrustworthy in consequence.  Here is a summary of the
tainting behavior of operators and functions that may be affected by
the locale:</p>
<ul>
<li>
<p><b>Comparison operators</b> (<code class="inline">lt</code>
, <code class="inline">le</code>
, <code class="inline">ge</code>
, <code class="inline">gt</code>
 and <code class="inline">cmp</code>
):</p>
<p>Scalar true/false (or less/equal/greater) result is never tainted.</p>
</li>
<li>
<p><b>Case-mapping interpolation</b> (with <code class="inline">\<span class="w">l</span></code>
, <code class="inline">\<span class="w">L</span></code>
, <code class="inline">\<span class="w">u</span></code>
 or <code class="inline">\<span class="w">U</span></code>
)</p>
<p>Result string containing interpolated material is tainted if
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 (but not <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
) is in effect.</p>
</li>
<li>
<p><b>Matching operator</b> (<code class="inline"><a class="l_k" href="functions/m.html">m//</a></code>):</p>
<p>Scalar true/false result never tainted.</p>
<p>Subpatterns, either delivered as a list-context result or as $1 etc.
are tainted if <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 (but not <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
)
is in effect, and the subpattern regular
expression contains <code class="inline">\<span class="w">w</span></code>
 (to match an alphanumeric character), <code class="inline">\<span class="w">W</span></code>

(non-alphanumeric character), <code class="inline">\s</code> (whitespace character), or <code class="inline">\<span class="w">S</span></code>

(non whitespace character).  The matched-pattern variable, $&amp;, $`
(pre-match), $' (post-match), and $+ (last match) are also tainted if
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 is in effect and the regular expression contains <code class="inline">\<span class="w">w</span></code>
,
<code class="inline">\<span class="w">W</span></code>
, <code class="inline">\s</code>, or <code class="inline">\<span class="w">S</span></code>
.</p>
</li>
<li>
<p><b>Substitution operator</b> (<code class="inline"><a class="l_k" href="functions/s.html">s///</a></code>):</p>
<p>Has the same behavior as the match operator.  Also, the left
operand of <code class="inline">=~</code>
 becomes tainted when <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>

(but not <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
) is in effect if modified as
a result of a substitution based on a regular
expression match involving <code class="inline">\<span class="w">w</span></code>
, <code class="inline">\<span class="w">W</span></code>
, <code class="inline">\s</code>, or <code class="inline">\<span class="w">S</span></code>
; or of
case-mapping with <code class="inline">\<span class="w">l</span></code>
, <code class="inline">\<span class="w">L</span></code>
,<code class="inline">\<span class="w">u</span></code>
 or <code class="inline">\<span class="w">U</span></code>
.</p>
</li>
<li>
<p><b>Output formatting functions</b> (printf() and write()):</p>
<p>Results are never tainted because otherwise even output from print,
for example <code class="inline"><a class="l_k" href="functions/print.html">print(1/7)</a></code>, should be tainted if <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 is in
effect.</p>
</li>
<li>
<p><b>Case-mapping functions</b> (lc(), lcfirst(), uc(), ucfirst()):</p>
<p>Results are tainted if <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 (but not
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span></code>
) is in effect.</p>
</li>
<li>
<p><b>POSIX locale-dependent functions</b> (localeconv(), strcoll(),
strftime(), strxfrm()):</p>
<p>Results are never tainted.</p>
</li>
<li>
<p><b>POSIX character class tests</b> (isalnum(), isalpha(), isdigit(),
isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(),
isxdigit()):</p>
<p>True/false results are never tainted.</p>
</li>
</ul>
<p>Three examples illustrate locale-dependent tainting.
The first program, which ignores its locale, won't run: a value taken
directly from the command line may not be used to name an output file
when taint checks are enabled.</p>
<pre class="verbatim"><ol><li>        <span class="c">#/usr/local/bin/perl -T</span></li><li>        <span class="c"># Run with taint checking</span></li><li></li><li>        <span class="c"># Command line sanity check omitted...</span></li><li>        <span class="i">$tainted_output_file</span> = <a class="l_k" href="functions/shift.html">shift</a><span class="sc">;</span></li><li></li><li>        <a class="l_k" href="functions/open.html">open</a><span class="s">(</span><span class="w">F</span><span class="cm">,</span> <span class="q">&quot;&gt;$tainted_output_file&quot;</span><span class="s">)</span></li><li>            <a class="l_k" href="functions/or.html">or</a> <a class="l_k" href="functions/warn.html">warn</a> <span class="q">&quot;Open of $tainted_output_file failed: $!\n&quot;</span><span class="sc">;</span></li></ol></pre><p>The program can be made to run by "laundering" the tainted value through
a regular expression: the second example--which still ignores locale
information--runs, creating the file named on its command line
if it can.</p>
<pre class="verbatim"><ol><li>        <span class="c">#/usr/local/bin/perl -T</span></li><li></li><li>        <span class="i">$tainted_output_file</span> = <a class="l_k" href="functions/shift.html">shift</a><span class="sc">;</span></li><li>        <span class="i">$tainted_output_file</span> =~ <span class="q">m%[\w/]+%</span><span class="sc">;</span></li><li>        <span class="i">$untainted_output_file</span> = <span class="i">$&amp;</span><span class="sc">;</span></li><li></li><li>        <a class="l_k" href="functions/open.html">open</a><span class="s">(</span><span class="w">F</span><span class="cm">,</span> <span class="q">&quot;&gt;$untainted_output_file&quot;</span><span class="s">)</span></li><li>            or <a class="l_k" href="functions/warn.html">warn</a> <span class="q">&quot;Open of $untainted_output_file failed: $!\n&quot;</span><span class="sc">;</span></li></ol></pre><p>Compare this with a similar but locale-aware program:</p>
<pre class="verbatim"><ol><li>        <span class="c">#/usr/local/bin/perl -T</span></li><li></li><li>        <span class="i">$tainted_output_file</span> = <a class="l_k" href="functions/shift.html">shift</a><span class="sc">;</span></li><li>        <a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span><span class="sc">;</span></li><li>        <span class="i">$tainted_output_file</span> =~ <span class="q">m%[\w/]+%</span><span class="sc">;</span></li><li>        <span class="i">$localized_output_file</span> = <span class="i">$&amp;</span><span class="sc">;</span></li><li></li><li>        <a class="l_k" href="functions/open.html">open</a><span class="s">(</span><span class="w">F</span><span class="cm">,</span> <span class="q">&quot;&gt;$localized_output_file&quot;</span><span class="s">)</span></li><li>            or <a class="l_k" href="functions/warn.html">warn</a> <span class="q">&quot;Open of $localized_output_file failed: $!\n&quot;</span><span class="sc">;</span></li></ol></pre><p>This third program fails to run because $&amp; is tainted: it is the result
of a match involving <code class="inline">\<span class="w">w</span></code>
 while <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 is in effect.</p>
<a name="ENVIRONMENT"></a><h1>ENVIRONMENT</h1>
<ul>
<li><a name="PERL_BADLANG"></a><b>PERL_BADLANG</b>
<p>A string that can suppress Perl's warning about failed locale settings
at startup.  Failure can occur if the locale support in the operating
system is lacking (broken) in some way--or if you mistyped the name of
a locale when you set up your environment.  If this environment
variable is absent, or has a value that does not evaluate to integer
zero--that is, "0" or ""-- Perl will complain about locale setting
failures.</p>
<p><b>NOTE</b>: PERL_BADLANG only gives you a way to hide the warning message.
The message tells about some problem in your system's locale support,
and you should investigate what the problem is.</p>
</li>
</ul>
<p>The following environment variables are not specific to Perl: They are
part of the standardized (ISO C, XPG4, POSIX 1.c) setlocale() method
for controlling an application's opinion on data.</p>
<ul>
<li><a name="LC_ALL"></a><b>LC_ALL</b>
<p><code class="inline"><span class="w">LC_ALL</span></code>
 is the "override-all" locale environment variable. If
set, it overrides all the rest of the locale environment variables.</p>
</li>
<li><a name="LANGUAGE"></a><b>LANGUAGE</b>
<p><b>NOTE</b>: <code class="inline"><span class="w">LANGUAGE</span></code>
 is a GNU extension, it affects you only if you
are using the GNU libc.  This is the case if you are using e.g. Linux.
If you are using "commercial" Unixes you are most probably <i>not</i>
using GNU libc and you can ignore <code class="inline"><span class="w">LANGUAGE</span></code>
.</p>
<p>However, in the case you are using <code class="inline"><span class="w">LANGUAGE</span></code>
: it affects the
language of informational, warning, and error messages output by
commands (in other words, it's like <code class="inline"><span class="w">LC_MESSAGES</span></code>
) but it has higher
priority than <code class="inline"><span class="w">LC_ALL</span></code>
.  Moreover, it's not a single value but
instead a "path" (":"-separated list) of <i>languages</i> (not locales).
See the GNU <code class="inline"><span class="w">gettext</span></code>
 library documentation for more information.</p>
</li>
<li><a name="LC_CTYPE"></a><b>LC_CTYPE</b>
<p>In the absence of <code class="inline"><span class="w">LC_ALL</span></code>
, <code class="inline"><span class="w">LC_CTYPE</span></code>
 chooses the character type
locale.  In the absence of both <code class="inline"><span class="w">LC_ALL</span></code>
 and <code class="inline"><span class="w">LC_CTYPE</span></code>
, <code class="inline"><span class="w">LANG</span></code>

chooses the character type locale.</p>
</li>
<li><a name="LC_COLLATE"></a><b>LC_COLLATE</b>
<p>In the absence of <code class="inline"><span class="w">LC_ALL</span></code>
, <code class="inline"><span class="w">LC_COLLATE</span></code>
 chooses the collation
(sorting) locale.  In the absence of both <code class="inline"><span class="w">LC_ALL</span></code>
 and <code class="inline"><span class="w">LC_COLLATE</span></code>
,
<code class="inline"><span class="w">LANG</span></code>
 chooses the collation locale.</p>
</li>
<li><a name="LC_MONETARY"></a><b>LC_MONETARY</b>
<p>In the absence of <code class="inline"><span class="w">LC_ALL</span></code>
, <code class="inline"><span class="w">LC_MONETARY</span></code>
 chooses the monetary
formatting locale.  In the absence of both <code class="inline"><span class="w">LC_ALL</span></code>
 and <code class="inline"><span class="w">LC_MONETARY</span></code>
,
<code class="inline"><span class="w">LANG</span></code>
 chooses the monetary formatting locale.</p>
</li>
<li><a name="LC_NUMERIC"></a><b>LC_NUMERIC</b>
<p>In the absence of <code class="inline"><span class="w">LC_ALL</span></code>
, <code class="inline"><span class="w">LC_NUMERIC</span></code>
 chooses the numeric format
locale.  In the absence of both <code class="inline"><span class="w">LC_ALL</span></code>
 and <code class="inline"><span class="w">LC_NUMERIC</span></code>
, <code class="inline"><span class="w">LANG</span></code>

chooses the numeric format.</p>
</li>
<li><a name="LC_TIME"></a><b>LC_TIME</b>
<p>In the absence of <code class="inline"><span class="w">LC_ALL</span></code>
, <code class="inline"><span class="w">LC_TIME</span></code>
 chooses the date and time
formatting locale.  In the absence of both <code class="inline"><span class="w">LC_ALL</span></code>
 and <code class="inline"><span class="w">LC_TIME</span></code>
,
<code class="inline"><span class="w">LANG</span></code>
 chooses the date and time formatting locale.</p>
</li>
<li><a name="LANG"></a><b>LANG</b>
<p><code class="inline"><span class="w">LANG</span></code>
 is the "catch-all" locale environment variable. If it is set, it
is used as the last resort after the overall <code class="inline"><span class="w">LC_ALL</span></code>
 and the
category-specific <code class="inline"><span class="w">LC_</span>...</code>
.</p>
</li>
</ul>
<a name="Examples"></a><h2>Examples</h2>
<p>The LC_NUMERIC controls the numeric output:</p>
<pre class="verbatim"><ol><li>   <a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(locale_h)</span><span class="sc">;</span> <span class="c"># Imports setlocale() and the LC_ constants.</span></li><li>   <span class="i">setlocale</span><span class="s">(</span><span class="w">LC_NUMERIC</span><span class="cm">,</span> <span class="q">&quot;fr_FR&quot;</span><span class="s">)</span> <a class="l_k" href="functions/or.html">or</a> <a class="l_k" href="functions/die.html">die</a> <span class="q">&quot;Pardon&quot;</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/printf.html">printf</a> <span class="q">&quot;%g\n&quot;</span><span class="cm">,</span> <span class="n">1.23</span><span class="sc">;</span> <span class="c"># If the &quot;fr_FR&quot; succeeded, probably shows 1,23.</span></li></ol></pre><p>and also how strings are parsed by POSIX::strtod() as numbers:</p>
<pre class="verbatim"><ol><li>   <a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(locale_h strtod)</span><span class="sc">;</span></li><li>   <span class="i">setlocale</span><span class="s">(</span><span class="w">LC_NUMERIC</span><span class="cm">,</span> <span class="q">&quot;de_DE&quot;</span><span class="s">)</span> <a class="l_k" href="functions/or.html">or</a> <a class="l_k" href="functions/die.html">die</a> <span class="q">&quot;Entschuldigung&quot;</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/my.html">my</a> <span class="i">$x</span> = <span class="i">strtod</span><span class="s">(</span><span class="q">&quot;2,34&quot;</span><span class="s">)</span> + <span class="n">5</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/print.html">print</a> <span class="i">$x</span><span class="cm">,</span> <span class="q">&quot;\n&quot;</span><span class="sc">;</span> <span class="c"># Probably shows 7,34.</span></li></ol></pre><a name="NOTES"></a><h1>NOTES</h1>
<a name="Backward-compatibility"></a><h2>Backward compatibility</h2>
<p>Versions of Perl prior to 5.004 <b>mostly</b> ignored locale information,
generally behaving as if something similar to the <code class="inline"><span class="q">&quot;C&quot;</span></code>
 locale were
always in force, even if the program environment suggested otherwise
(see <a href="#The-setlocale-function">The setlocale function</a>).  By default, Perl still behaves this
way for backward compatibility.  If you want a Perl application to pay
attention to locale information, you <b>must</b> use the <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>

pragma (see <a href="#The-use-locale-pragma">The use locale pragma</a>) or, in the unlikely event
that you want to do so for just pattern matching, the
<code class="inline"><span class="q">/l</span></code>
 regular expression modifier (see <a href="perlre.html#Character-set-modifiers">Character set modifiers in perlre</a>) to instruct it to do so.</p>
<p>Versions of Perl from 5.002 to 5.003 did use the <code class="inline"><span class="w">LC_CTYPE</span></code>

information if available; that is, <code class="inline">\<span class="w">w</span></code>
 did understand what
were the letters according to the locale environment variables.
The problem was that the user had no control over the feature:
if the C library supported locales, Perl used them.</p>
<a name="I18N%3aCollate-obsolete"></a><h2>I18N:Collate obsolete</h2>
<p>In versions of Perl prior to 5.004, per-locale collation was possible
using the <code class="inline"><span class="w">I18N::Collate</span></code>
 library module.  This module is now mildly
obsolete and should be avoided in new applications.  The <code class="inline"><span class="w">LC_COLLATE</span></code>

functionality is now integrated into the Perl core language: One can
use locale-specific scalar data completely normally with <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
,
so there is no longer any need to juggle with the scalar references of
<code class="inline"><span class="w">I18N::Collate</span></code>
.</p>
<a name="Sort-speed-and-memory-use-impacts"></a><h2>Sort speed and memory use impacts</h2>
<p>Comparing and sorting by locale is usually slower than the default
sorting; slow-downs of two to four times have been observed.  It will
also consume more memory: once a Perl scalar variable has participated
in any string comparison or sorting operation obeying the locale
collation rules, it will take 3-15 times more memory than before.  (The
exact multiplier depends on the string's contents, the operating system
and the locale.) These downsides are dictated more by the operating
system's implementation of the locale system than by Perl.</p>
<a name="write()-and-LC_NUMERIC"></a><h2>write() and LC_NUMERIC</h2>
<p>If a program's environment specifies an LC_NUMERIC locale and <code class="inline"><a class="l_k" href="functions/use.html">use</a>
<span class="w">locale</span></code>
 is in effect when the format is declared, the locale is used
to specify the decimal point character in formatted output.  Formatted
output cannot be controlled by <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 at the time when write()
is called.</p>
<a name="Freely-available-locale-definitions"></a><h2>Freely available locale definitions</h2>
<p>The Unicode CLDR project extracts the POSIX portion of many of its
locales, available at</p>
<pre class="verbatim"><ol><li>  <span class="j">http:</span><span class="q">//</span><span class="w">unicode</span>.<span class="w">org</span>/<span class="w">Public</span>/<span class="w">cldr</span><span class="q">/latest/</span></li></ol></pre><p>There is a large collection of locale definitions at:</p>
<pre class="verbatim"><ol><li>  http://std.dkuug.dk/i18n/WG15-collection/locales/</li></ol></pre><p>You should be aware that it is
unsupported, and is not claimed to be fit for any purpose.  If your
system allows installation of arbitrary locales, you may find the
definitions useful as they are, or as a basis for the development of
your own locales.</p>
<a name="I18n-and-l10n"></a><h2>I18n and l10n</h2>
<p>"Internationalization" is often abbreviated as <b>i18n</b> because its first
and last letters are separated by eighteen others.  (You may guess why
the internalin ... internaliti ... i18n tends to get abbreviated.)  In
the same way, "localization" is often abbreviated to <b>l10n</b>.</p>
<a name="An-imperfect-standard"></a><h2>An imperfect standard</h2>
<p>Internationalization, as defined in the C and POSIX standards, can be
criticized as incomplete, ungainly, and having too large a granularity.
(Locales apply to a whole process, when it would arguably be more useful
to have them apply to a single thread, window group, or whatever.)  They
also have a tendency, like standards groups, to divide the world into
nations, when we all know that the world can equally well be divided
into bankers, bikers, gamers, and so on.</p>
<a name="Unicode-and-UTF-8"></a><h1>Unicode and UTF-8</h1>
<p>The support of Unicode is new starting from Perl version v5.6, and more fully
implemented in version v5.8 and later.  See <a href="perluniintro.html">perluniintro</a>.  It is
strongly recommended that when combining Unicode and locale (starting in
v5.16), you use</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span> <span class="q">&#39;:not_characters&#39;</span><span class="sc">;</span></li></ol></pre><p>When this form of the pragma is used, only the non-character portions of
locales are used by Perl, for example <code class="inline"><span class="w">LC_NUMERIC</span></code>
.  Perl assumes that
you have translated all the characters it is to operate on into Unicode
(actually the platform's native character set (ASCII or EBCDIC) plus
Unicode).  For data in files, this can conveniently be done by also
specifying</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <a class="l_k" href="functions/open.html">open</a> <span class="q">&#39;:locale&#39;</span><span class="sc">;</span></li></ol></pre><p>This pragma arranges for all inputs from files to be translated into
Unicode from the current locale as specified in the environment (see
<a href="#ENVIRONMENT">ENVIRONMENT</a>), and all outputs to files to be translated back
into the locale.  (See <a href="open.html">open</a>).  On a per-filehandle basis, you can
instead use the <a href="http://search.cpan.org/perldoc/PerlIO::locale">PerlIO::locale</a> module, or the <a href="http://search.cpan.org/perldoc/Encode::Locale">Encode::Locale</a>
module, both available from CPAN.  The latter module also has methods to
ease the handling of <code class="inline"><span class="w">ARGV</span></code>
 and environment variables, and can be used
on individual strings.  Also, if you know that all your locales will be
UTF-8, as many are these days, you can use the <a href="perlrun.html#-C">-C</a>
command line switch.</p>
<p>This form of the pragma allows essentially seamless handling of locales
with Unicode.  The collation order will be Unicode's.  It is strongly
recommended that when you need to order and sort strings that you use
the standard module <a href="Unicode/Collate.html">Unicode::Collate</a> which gives much better results
in many instances than you can get with the old-style locale handling.</p>
<p>For pre-v5.16 Perls, or if you use the locale pragma without the
<code class="inline"><span class="j">:</span><span class="w">not_characters</span></code>
 parameter, Perl tries to work with both Unicode and
locales--but there are problems.</p>
<p>Perl does not handle multi-byte locales in this case, such as have been
used for various
Asian languages, such as Big5 or Shift JIS.  However, the increasingly
common multi-byte UTF-8 locales, if properly implemented, may work
reasonably well (depending on your C library implementation) in this
form of the locale pragma, simply because both
they and Perl store characters that take up multiple bytes the same way.
However, some, if not most, C library implementations may not process
the characters in the upper half of the Latin-1 range (128 - 255)
properly under LC_CTYPE.  To see if a character is a particular type
under a locale, Perl uses the functions like <code class="inline"><span class="i">isalnum</span><span class="s">(</span><span class="s">)</span></code>
.  Your C
library may not work for UTF-8 locales with those functions, instead
only working under the newer wide library functions like <code class="inline"><span class="i">iswalnum</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<p>Perl generally takes the tack to use locale rules on code points that can fit
in a single byte, and Unicode rules for those that can't (though this
isn't uniformly applied, see the note at the end of this section).  This
prevents many problems in locales that aren't UTF-8.  Suppose the locale
is ISO8859-7, Greek.  The character at 0xD7 there is a capital Chi. But
in the ISO8859-1 locale, Latin1, it is a multiplication sign.  The POSIX
regular expression character class <code class="inline"><span class="s">[</span><span class="s">[</span><span class="co">:</span><span class="w">alpha</span><span class="co">:</span><span class="s">]</span><span class="s">]</span></code>
 will magically match
0xD7 in the Greek locale but not in the Latin one.</p>
<p>However, there are places where this breaks down.  Certain constructs are
for Unicode only, such as <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Alpha</span><span class="s">}</span></code>
.  They assume that 0xD7 always has its
Unicode meaning (or the equivalent on EBCDIC platforms).  Since Latin1 is a
subset of Unicode and 0xD7 is the multiplication sign in both Latin1 and
Unicode, <code class="inline">\<span class="i">p</span><span class="s">{</span><span class="w">Alpha</span><span class="s">}</span></code>
 will never match it, regardless of locale.  A similar
issue occurs with <code class="inline">\<span class="i">N</span><span class="s">{</span>...<span class="s">}</span></code>
.  It is therefore a bad idea to use <code class="inline">\<span class="w">p</span><span class="s">{</span><span class="s">}</span></code>
 or
<code class="inline">\<span class="w">N</span><span class="s">{</span><span class="s">}</span></code>
 under plain <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
--<i>unless</i> you can guarantee that the
locale will be a ISO8859-1.  Use POSIX character classes instead.</p>
<p>Another problem with this approach is that operations that cross the
single byte/multiple byte boundary are not well-defined, and so are
disallowed.  (This boundary is between the codepoints at 255/256.).
For example, lower casing LATIN CAPITAL LETTER Y WITH DIAERESIS (U+0178)
should return LATIN SMALL LETTER Y WITH DIAERESIS (U+00FF).  But in the
Greek locale, for example, there is no character at 0xFF, and Perl
has no way of knowing what the character at 0xFF is really supposed to
represent.  Thus it disallows the operation.  In this mode, the
lowercase of U+0178 is itself.</p>
<p>The same problems ensue if you enable automatic UTF-8-ification of your
standard file handles, default <code class="inline"><a class="l_k" href="functions/open.html">open()</a></code> layer, and <code class="inline"><span class="i">@ARGV</span></code>
 on non-ISO8859-1,
non-UTF-8 locales (by using either the <b>-C</b> command line switch or the
<code class="inline"><span class="w">PERL_UNICODE</span></code>
 environment variable; see <a href="perlrun.html">perlrun</a>).
Things are read in as UTF-8, which would normally imply a Unicode
interpretation, but the presence of a locale causes them to be interpreted
in that locale instead.  For example, a 0xD7 code point in the Unicode
input, which should mean the multiplication sign, won't be interpreted by
Perl that way under the Greek locale.  This is not a problem
<i>provided</i> you make certain that all locales will always and only be either
an ISO8859-1, or, if you don't have a deficient C library, a UTF-8 locale.</p>
<p>Vendor locales are notoriously buggy, and it is difficult for Perl to test
its locale-handling code because this interacts with code that Perl has no
control over; therefore the locale-handling code in Perl may be buggy as
well.  (However, the Unicode-supplied locales should be better, and
there is a feed back mechanism to correct any problems.  See
<a href="#Freely-available-locale-definitions">Freely available locale definitions</a>.)</p>
<p>If you have Perl v5.16, the problems mentioned above go away if you use
the <code class="inline"><span class="j">:</span><span class="w">not_characters</span></code>
 parameter to the locale pragma (except for vendor
bugs in the non-character portions).  If you don't have v5.16, and you
<i>do</i> have locales that work, using them may be worthwhile for certain
specific purposes, as long as you keep in mind the gotchas already
mentioned.  For example, if the collation for your locales works, it
runs faster under locales than under <a href="Unicode/Collate.html">Unicode::Collate</a>; and you gain
access to such things as the local currency symbol and the names of the
months and days of the week.  (But to hammer home the point, in v5.16,
you get this access without the downsides of locales by using the
<code class="inline"><span class="j">:</span><span class="w">not_characters</span></code>
 form of the pragma.)</p>
<p>Note: The policy of using locale rules for code points that can fit in a
byte, and Unicode rules for those that can't is not uniformly applied.
Pre-v5.12, it was somewhat haphazard; in v5.12 it was applied fairly
consistently to regular expression matching except for bracketed
character classes; in v5.14 it was extended to all regex matches; and in
v5.16 to the casing operations such as <code class="inline"><span class="q">&quot;\L&quot;</span></code>
 and <code class="inline"><a class="l_k" href="functions/uc.html">uc()</a></code>.  For
collation, in all releases, the system's <code class="inline"><span class="i">strxfrm</span><span class="s">(</span><span class="s">)</span></code>
 function is called,
and whatever it does is what you get.</p>
<a name="BUGS"></a><h1>BUGS</h1>
<a name="Broken-systems"></a><h2>Broken systems</h2>
<p>In certain systems, the operating system's locale support
is broken and cannot be fixed or used by Perl.  Such deficiencies can
and will result in mysterious hangs and/or Perl core dumps when
<code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
 is in effect.  When confronted with such a system,
please report in excruciating detail to &lt;<i>perlbug@perl.org</i>&gt;, and
also contact your vendor: bug fixes may exist for these problems
in your operating system.  Sometimes such bug fixes are called an
operating system upgrade.</p>
<a name="SEE-ALSO"></a><h1>SEE ALSO</h1>
<p><a href="I18N/Langinfo.html">I18N::Langinfo</a>, <a href="perluniintro.html">perluniintro</a>, <a href="perlunicode.html">perlunicode</a>, <a href="open.html">open</a>,
<a href="POSIX.html#isalnum">isalnum in POSIX</a>, <a href="POSIX.html#isalpha">isalpha in POSIX</a>,
<a href="POSIX.html#isdigit">isdigit in POSIX</a>, <a href="POSIX.html#isgraph">isgraph in POSIX</a>, <a href="POSIX.html#islower">islower in POSIX</a>,
<a href="POSIX.html#isprint">isprint in POSIX</a>, <a href="POSIX.html#ispunct">ispunct in POSIX</a>, <a href="POSIX.html#isspace">isspace in POSIX</a>,
<a href="POSIX.html#isupper">isupper in POSIX</a>, <a href="POSIX.html#isxdigit">isxdigit in POSIX</a>, <a href="POSIX.html#localeconv">localeconv in POSIX</a>,
<a href="POSIX.html#setlocale">setlocale in POSIX</a>, <a href="POSIX.html#strcoll">strcoll in POSIX</a>, <a href="POSIX.html#strftime">strftime in POSIX</a>,
<a href="POSIX.html#strtod">strtod in POSIX</a>, <a href="POSIX.html#strxfrm">strxfrm in POSIX</a>.</p>
<a name="HISTORY"></a><h1>HISTORY</h1>
<p>Jarkko Hietaniemi's original <i>perli18n.pod</i> heavily hacked by Dominic
Dunlop, assisted by the perl5-porters.  Prose worked over a bit by
Tom Christiansen, and updated by Perl 5 porters.</p>




  <div id="page_index" class="hud_container">
    <div id="page_index_header" class="hud_header">
      <div id="page_index_close" class="hud_close"><a href="#" onClick="pageIndex.hide();return false;"></a></div>
      <div id="page_index_title" class="hud_title"><span class="hud_span_top">Page index</span></div>
      <div id="page_index_topright" class="hud_topright"></div>
    </div>
    <div id="page_index_content" class="hud_content">
      <ul><li><a href="#NAME">NAME</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#WHAT-IS-A-LOCALE">WHAT IS A LOCALE</a><li><a href="#PREPARING-TO-USE-LOCALES">PREPARING TO USE LOCALES</a><li><a href="#USING-LOCALES">USING LOCALES</a><ul><li><a href="#The-use-locale-pragma">The use locale pragma</a><li><a href="#The-setlocale-function">The setlocale function</a><li><a href="#Finding-locales">Finding locales</a><li><a href="#LOCALE-PROBLEMS">LOCALE PROBLEMS</a><li><a href="#Temporarily-fixing-locale-problems">Temporarily fixing locale problems</a><li><a href="#Permanently-fixing-locale-problems">Permanently fixing locale problems</a><li><a href="#Permanently-fixing-your-system's-locale-configuration">Permanently fixing your system's locale configuration</a><li><a href="#Fixing-system-locale-configuration">Fixing system locale configuration</a><li><a href="#The-localeconv-function">The localeconv function</a><li><a href="#I18N%3a%3aLanginfo">I18N::Langinfo</a></ul><li><a href="#LOCALE-CATEGORIES">LOCALE CATEGORIES</a><ul><li><a href="#Category-LC_COLLATE%3a-Collation">Category LC_COLLATE: Collation</a><li><a href="#Category-LC_CTYPE%3a-Character-Types">Category LC_CTYPE: Character Types</a><li><a href="#Category-LC_NUMERIC%3a-Numeric-Formatting">Category LC_NUMERIC: Numeric Formatting</a><li><a href="#Category-LC_MONETARY%3a-Formatting-of-monetary-amounts">Category LC_MONETARY: Formatting of monetary amounts</a><li><a href="#LC_TIME">LC_TIME</a><li><a href="#Other-categories">Other categories</a></ul><li><a href="#SECURITY">SECURITY</a><li><a href="#ENVIRONMENT">ENVIRONMENT</a><ul><li><a href="#Examples">Examples</a></ul><li><a href="#NOTES">NOTES</a><ul><li><a href="#Backward-compatibility">Backward compatibility</a><li><a href="#I18N%3aCollate-obsolete">I18N:Collate obsolete</a><li><a href="#Sort-speed-and-memory-use-impacts">Sort speed and memory use impacts</a><li><a href="#write()-and-LC_NUMERIC">write() and LC_NUMERIC</a><li><a href="#Freely-available-locale-definitions">Freely available locale definitions</a><li><a href="#I18n-and-l10n">I18n and l10n</a><li><a href="#An-imperfect-standard">An imperfect standard</a></ul><li><a href="#Unicode-and-UTF-8">Unicode and UTF-8</a><li><a href="#BUGS">BUGS</a><ul><li><a href="#Broken-systems">Broken systems</a></ul><li><a href="#SEE-ALSO">SEE ALSO</a><li><a href="#HISTORY">HISTORY</a></ul>
    </div>
    <div id="page_index_footer" class="hud_footer">
      <div id="page_index_bottomleft" class="hud_bottomleft"></div>
      <div id="page_index_bottom" class="hud_bottom"><span class="hud_span_bottom"></span></div>
      <div id="page_index_resize" class="hud_resize"></div>
    </div>
  </div>


	    &nbsp;
          </div>
          <div id="content_footer">
          </div>
        </div>
        <div class="clear"></div>
      </div>
      
    <div id="footer">
      <div id="footer_content">
        <div id="footer_strapline">
          perldoc.perl.org - Official documentation for the Perl programming language
        </div>
        <div id="footer_links">
          <div id="address">
            <p class="name">Contact details</p>
            <p class="address">
	      Site maintained by <a href="mailto:jj@jonallen.info">Jon Allen (JJ)</a><br>
	    </p>
            <p class="contact">
              Documentation maintained by the <a href="http://lists.cpan.org/showlist.cgi?name=perl5-porters">Perl 5 Porters</a>
            </p>
          </div>
          <ul class="f1">
            <li>Manual
              <ul class="f2">
                <li><a href="index-overview.html">Overview</a>
                <li><a href="index-tutorials.html">Tutorials</a>
                <li><a href="index-faq.html">FAQs</a>
                <li><a href="index-history.html">Changes</a>
              </ul>
            <li>Reference
              <ul class="f2">
                <li><a href="index-language.html">Language</a>
                <li><a href="index-functions.html">Functions</a>
                <li><a href="perlop.html">Operators</a>
                <li><a href="perlvar.html">Variables</a>
              </ul>
            <li>Modules
              <ul class="f2">
                <li><a href="index-modules-A.html">Modules</a>
                <li><a href="index-pragmas.html">Pragmas</a>
                <li><a href="index-utilities.html">Utilities</a>
              </ul>
            <li>Misc
              <ul class="f2">
                <li><a href="index-licence.html">License</a>
                <li><a href="index-internals.html">Internals</a>
                <li><a href="index-platforms.html">Platforms</a>
              </ul>          </ul>
          <div class="clear"></div>
        </div>
      </div>
      <div id="footer_end">
      </div>
    </div>
      
    </div>
      <script language="JavaScript" type="text/javascript" src="static/exploreperl.js"></script>
      <script language="JavaScript" src="static/combined-20100403.js" type="text/javascript"></script>
<script language="JavaScript" type="text/javascript">
  perldoc.setPath(0);
  perldoc.pageName    = 'perllocale';
  perldoc.pageAddress = 'perllocale.html';
  perldoc.contentPage = 1;
  explorePerl.render();
  explorePerl.addEvents('explore_anchor');
</script>
    
  </body>
</html>