File: mb-detect-encoding.xml

package info (click to toggle)
php-doc 20241205~git.dfcbb86%2Bdfsg-1
  • links: PTS, VCS
  • area: main
  • in suites: trixie
  • size: 70,956 kB
  • sloc: xml: 968,269; php: 23,883; javascript: 671; sh: 177; makefile: 37
file content (251 lines) | stat: -rw-r--r-- 7,765 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
<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.mb-detect-encoding" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>mb_detect_encoding</refname>
  <refpurpose>Detect character encoding</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>string</type><type>false</type></type><methodname>mb_detect_encoding</methodname>
   <methodparam><type>string</type><parameter>string</parameter></methodparam>
   <methodparam choice="opt"><type class="union"><type>array</type><type>string</type><type>null</type></type><parameter>encodings</parameter><initializer>&null;</initializer></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>strict</parameter><initializer>&false;</initializer></methodparam>
  </methodsynopsis>
  <para>
   Detects the most likely character encoding for <type>string</type> <parameter>string</parameter>
   from an ordered list of candidates.
  </para>
  <para>
   Automatic detection of the intended character encoding can never be entirely reliable;
   without some additional information, it is similar to decoding an encrypted string
   without the key. It is always preferable to use an indication of character encoding
   stored or transmitted with the data, such as a "Content-Type" HTTP header.
  </para>
  <para>
   This function is most useful with multibyte encodings, where not all sequences of
   bytes form a valid string. If the input string contains such a sequence, that
   encoding will be rejected, and the next encoding checked.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>string</parameter></term>
     <listitem>
      <para>
       The <type>string</type> being inspected.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>encodings</parameter></term>
     <listitem>
      <para>
       A list of character encodings to try, in order. The list may be specified as
       an array of strings, or a single string separated by commas.
      </para>
      <para>
       If <parameter>encodings</parameter> is omitted or &null;,
       the current detect_order (set with the <link linkend="ini.mbstring.detect-order">
       mbstring.detect_order</link> configuration option, or <function>mb_detect_order</function>
       function) will be used.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>strict</parameter></term>
     <listitem>
      <para>
       Controls the behaviour when <parameter>string</parameter>
       is not valid in any of the listed <parameter>encodings</parameter>.
       If <parameter>strict</parameter> is set to &false;, the closest matching
       encoding will be returned; if <parameter>strict</parameter> is set to &true;,
       &false; will be returned.
      </para>
      <para>
       The default value for <parameter>strict</parameter> can be set
       with the <link linkend="ini.mbstring.strict-detection">
       mbstring.strict_detection</link> configuration option.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   The detected character encoding, or &false; if the string is not valid
   in any of the listed encodings.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry>8.2.0</entry>
      <entry>
       <function>mb_detect_encoding</function> will no longer return
       the following non text encodings:
       <literal>"Base64"</literal>, <literal>"QPrint"</literal>,
       <literal>"UUencode"</literal>, <literal>"HTML entities"</literal>,
       <literal>"7 bit"</literal> and <literal>"8 bit"</literal>.
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>mb_detect_encoding</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
// Detect character encoding with current detect_order
echo mb_detect_encoding($str);

// "auto" is expanded according to mbstring.language
echo mb_detect_encoding($str, "auto");

// Specify "encodings" parameter by list separated by comma
echo mb_detect_encoding($str, "JIS, eucjp-win, sjis-win");

// Use array to specify "encodings" parameter
$encodings = [
  "ASCII",
  "JIS",
  "EUC-JP"
];
echo mb_detect_encoding($str, $encodings);
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example>
    <title>Effect of <parameter>strict</parameter> parameter</title>
    <programlisting role="php">
     <![CDATA[
<?php
// 'áéóú' encoded in ISO-8859-1
$str = "\xE1\xE9\xF3\xFA";

// The string is not valid ASCII or UTF-8, but UTF-8 is considered a closer match
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8'], false));
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8'], true));

// If a valid encoding is found, the strict parameter does not change the result
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8', 'ISO-8859-1'], false));
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8', 'ISO-8859-1'], true));
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
string(5) "UTF-8"
bool(false)
string(10) "ISO-8859-1"
string(10) "ISO-8859-1"
]]>
    </screen>
   </example>
  </para>
  <para>
   In some cases, the same sequence of bytes may form a valid string in multiple
   character encodings, and it is impossible to know which interpretation was
   intended. For instance, among many others, the byte sequence "\xC4\xA2" could be:
  </para>
  <para>
   <simplelist>
    <member>
     "Ä¢" (U+00C4 LATIN CAPITAL LETTER A WITH DIAERESIS followed by U+00A2 CENT SIGN)
     encoded in any of ISO-8859-1, ISO-8859-15, or Windows-1252
    </member>
    <member>
     "ФЂ" (U+0424 CYRILLIC CAPITAL LETTER EF followed by U+0402 CYRILLIC CAPITAL LETTER
     DJE) encoded in ISO-8859-5
    </member>
    <member>
     "Ģ" (U+0122 LATIN CAPITAL LETTER G WITH CEDILLA) encoded in UTF-8
    </member>
   </simplelist>
  </para>
  <para>
   <example>
    <title>Effect of order when multiple encodings match</title>
    <programlisting role="php">
     <![CDATA[
<?php
$str = "\xC4\xA2";

// The string is valid in all three encodings, so the first one listed will be returned
var_dump(mb_detect_encoding($str, ['UTF-8', 'ISO-8859-1', 'ISO-8859-5']));
var_dump(mb_detect_encoding($str, ['ISO-8859-1', 'ISO-8859-5', 'UTF-8']));
var_dump(mb_detect_encoding($str, ['ISO-8859-5', 'UTF-8', 'ISO-8859-1']));
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
string(5) "UTF-8"
string(10) "ISO-8859-1"
string(10) "ISO-8859-5"
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>mb_detect_order</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->