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
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<HTML>
<HEAD>
<TITLE>AARM95 - The Generic Package Interfaces.C.Pointers</TITLE>
<META NAME="Author" CONTENT="JTC1/SC22/WG9/ARG, by Randall Brukardt, ARG Editor">
<META NAME="GENERATOR" CONTENT="Arm_Form.Exe, Ada Reference Manual generator">
<STYLE type="text/css">
DIV.paranum {position: absolute; font-family: Arial, Helvetica, sans-serif; left: 0.5 em; top: auto}
TT {font-family: "Courier New", monospace}
DT {display: compact}
DIV.Normal {font-family: "Times New Roman", Times, serif; margin-bottom: 0.6em}
DIV.Wide {font-family: "Times New Roman", Times, serif; margin-top: 0.6em; margin-bottom: 0.6em}
DIV.Annotations {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-bottom: 0.6em}
DIV.WideAnnotations {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-top: 0.6em; margin-bottom: 0.6em}
DIV.Index {font-family: "Times New Roman", Times, serif}
DIV.SyntaxSummary {font-family: "Times New Roman", Times, serif; margin-left: 2.0em; margin-bottom: 0.4em}
DIV.Notes {font-family: "Times New Roman", Times, serif; margin-left: 2.0em; margin-bottom: 0.6em}
DIV.NotesHeader {font-family: "Times New Roman", Times, serif; margin-left: 2.0em}
DIV.SyntaxIndented {font-family: "Times New Roman", Times, serif; margin-left: 2.0em; margin-bottom: 0.4em}
DIV.Indented {font-family: "Times New Roman", Times, serif; margin-left: 6.0em; margin-bottom: 0.6em}
DIV.CodeIndented {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-bottom: 0.6em}
DIV.SmallIndented {font-family: "Times New Roman", Times, serif; margin-left: 10.0em; margin-bottom: 0.6em}
DIV.SmallCodeIndented {font-family: "Times New Roman", Times, serif; margin-left: 8.0em; margin-bottom: 0.6em}
DIV.Examples {font-family: "Courier New", monospace; margin-left: 2.0em; margin-bottom: 0.6em}
DIV.SmallExamples {font-family: "Courier New", monospace; font-size: 80%; margin-left: 7.5em; margin-bottom: 0.6em}
DIV.IndentedExamples {font-family: "Courier New", monospace; margin-left: 8.0em; margin-bottom: 0.6em}
DIV.SmallIndentedExamples {font-family: "Courier New", monospace; font-size: 80%; margin-left: 15.0em; margin-bottom: 0.6em}
UL.Bulleted {font-family: "Times New Roman", Times, serif; margin-left: 2.0em; margin-right: 2.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.SmallBulleted {font-family: "Times New Roman", Times, serif; margin-left: 6.0em; margin-right: 6.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.NestedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-right: 4.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.SmallNestedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 8.0em; margin-right: 8.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.IndentedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 8.0em; margin-right: 8.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.CodeIndentedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 6.0em; margin-right: 6.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.CodeIndentedNestedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 8.0em; margin-right: 8.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.SyntaxIndentedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-right: 4.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.NotesBulleted {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-right: 4.0em; margin-top: 0em; margin-bottom: 0.5em}
UL.NotesNestedBulleted {font-family: "Times New Roman", Times, serif; margin-left: 6.0em; margin-right: 6.0em; margin-top: 0em; margin-bottom: 0.5em}
DL.Hanging {font-family: "Times New Roman", Times, serif; margin-top: 0em; margin-bottom: 0.6em}
DD.Hanging {margin-left: 6.0em}
DL.IndentedHanging {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-top: 0em; margin-bottom: 0.6em}
DD.IndentedHanging {margin-left: 2.0em}
DL.HangingInBulleted {font-family: "Times New Roman", Times, serif; margin-left: 2.0em; margin-right: 2.0em; margin-top: 0em; margin-bottom: 0.5em}
DD.HangingInBulleted {margin-left: 4.0em}
DL.SmallHanging {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-top: 0em; margin-bottom: 0.6em}
DD.SmallHanging {margin-left: 7.5em}
DL.SmallIndentedHanging {font-family: "Times New Roman", Times, serif; margin-left: 8.0em; margin-top: 0em; margin-bottom: 0.6em}
DD.SmallIndentedHanging {margin-left: 2.0em}
DL.SmallHangingInBulleted {font-family: "Times New Roman", Times, serif; margin-left: 6.0em; margin-right: 6.0em; margin-top: 0em; margin-bottom: 0.5em}
DD.SmallHangingInBulleted {margin-left: 5.0em}
DL.Enumerated {font-family: "Times New Roman", Times, serif; margin-right: 0.0em; margin-top: 0em; margin-bottom: 0.5em}
DD.Enumerated {margin-left: 2.0em}
DL.SmallEnumerated {font-family: "Times New Roman", Times, serif; margin-left: 4.0em; margin-right: 4.0em; margin-top: 0em; margin-bottom: 0.5em}
DD.SmallEnumerated {margin-left: 2.5em}
DL.NestedEnumerated {font-family: "Times New Roman", Times, serif; margin-left: 2.0em; margin-right: 2.0em; margin-top: 0em; margin-bottom: 0.5em}
DL.SmallNestedEnumerated {font-family: "Times New Roman", Times, serif; margin-left: 6.0em; margin-right: 6.0em; margin-top: 0em; margin-bottom: 0.5em}
</STYLE>
</HEAD>
<BODY TEXT="#000000" BGCOLOR="#FFFFF0" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000">
<P><A HREF="AA-TOC.html">Contents</A> <A HREF="AA-0-29.html">Index</A> <A HREF="AA-B-3-1.html">Previous</A> <A HREF="AA-B-4.html">Next</A></P>
<HR>
<H1> B.3.2 The Generic Package Interfaces.C.Pointers</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> The generic package Interfaces.C.Pointers allows
the Ada programmer to perform C-style operations on pointers. It includes
an access type Pointer, Value functions that dereference a Pointer and
deliver the designated array, several pointer arithmetic operations,
and ``copy'' procedures that copy the contents of a source pointer into
the array designated by a destination pointer. As in C, it treats an
object Ptr of type Pointer as a pointer to the first element of an array,
so that for example, adding 1 to Ptr yields a pointer to the second element
of the array.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="Normal"> The generic allows two styles of usage: one in
which the array is terminated by a special terminator element; and another
in which the programmer needs to keep track of the length. </DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> The generic library
package Interfaces.C.Pointers has the following declaration: </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="Examples"><TT><B>generic</B><BR>
<B>type</B> Index <B>is</B> (<>);<BR>
<B>type</B> Element <B>is</B> <B>private</B>;<BR>
<B>type</B> Element_Array <B>is</B> <B>array</B> (Index <B>range</B> <>) <B>of</B> <B>aliased</B> Element;<BR>
Default_Terminator : Element;<BR>
<B>package</B> Interfaces.C.Pointers <B>is</B><A NAME="I6467"></A><A NAME="I6468"></A><A NAME="I6469"></A><BR>
<B>pragma</B> Preelaborate(Pointers);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Examples"><TT> <B>type</B> <A NAME="I6470"></A><A NAME="I6471"></A>Pointer <B>is</B> <B>access</B> <B>all</B> Element;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Examples"><TT> <B>function</B> <A NAME="I6472"></A><A NAME="I6473"></A>Value(Ref : <B>in</B> Pointer;<BR>
Terminator : <B>in</B> Element := Default_Terminator)<BR>
<B>return</B> Element_Array;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Examples"><TT> <B>function</B> <A NAME="I6474"></A><A NAME="I6475"></A>Value(Ref : <B>in</B> Pointer;<BR>
Length : <B>in</B> ptrdiff_t)<BR>
<B>return</B> Element_Array;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="Examples"><TT> <A NAME="I6476"></A>Pointer_Error : <B>exception</B>;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="Examples"><TT> <I>-- C-style Pointer arithmetic</I></TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="Examples"><TT> <B>function</B> "+" (Left : <B>in</B> Pointer; Right : <B>in</B> ptrdiff_t) <B>return</B> Pointer;<BR>
<B>function</B> "+" (Left : <B>in</B> ptrdiff_t; Right : <B>in</B> Pointer) <B>return</B> Pointer;<BR>
<B>function</B> "-" (Left : <B>in</B> Pointer; Right : <B>in</B> ptrdiff_t) <B>return</B> Pointer;<BR>
<B>function</B> "-" (Left : <B>in</B> Pointer; Right : <B>in</B> Pointer) <B>return</B> ptrdiff_t;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11</FONT></DIV>
<DIV Class="Examples"><TT> <B>procedure</B> <A NAME="I6477"></A><A NAME="I6478"></A>Increment (Ref : <B>in</B> <B>out</B> Pointer);<BR>
<B>procedure</B> <A NAME="I6479"></A><A NAME="I6480"></A>Decrement (Ref : <B>in</B> <B>out</B> Pointer);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>12</FONT></DIV>
<DIV Class="Examples"><TT> <B>pragma</B> Convention (Intrinsic, "+");<BR>
<B>pragma</B> Convention (Intrinsic, "-");<BR>
<B>pragma</B> Convention (Intrinsic, Increment);<BR>
<B>pragma</B> Convention (Intrinsic, Decrement);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>13</FONT></DIV>
<DIV Class="Examples"><TT> <B>function</B> <A NAME="I6481"></A><A NAME="I6482"></A>Virtual_Length (Ref : <B>in</B> Pointer;<BR>
Terminator : <B>in</B> Element := Default_Terminator)<BR>
<B>return</B> ptrdiff_t;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>14</FONT></DIV>
<DIV Class="Examples"><TT> <B>procedure</B> <A NAME="I6483"></A><A NAME="I6484"></A>Copy_Terminated_Array<BR>
(Source : <B>in</B> Pointer;<BR>
Target : <B>in</B> Pointer;<BR>
Limit : <B>in</B> ptrdiff_t := ptrdiff_t'Last;<BR>
Terminator : <B>in</B> Element := Default_Terminator);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>15</FONT></DIV>
<DIV Class="Examples"><TT> <B>procedure</B> <A NAME="I6485"></A><A NAME="I6486"></A>Copy_Array (Source : <B>in</B> Pointer;<BR>
Target : <B>in</B> Pointer;<BR>
Length : <B>in</B> ptrdiff_t);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>16</FONT></DIV>
<DIV Class="Examples"><TT><B>end</B> Interfaces.C.Pointers;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>17</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> The type Pointer
is C-compatible and corresponds to one use of C's ``Element *''. An object
of type Pointer is interpreted as a pointer to the initial Element in
an Element_Array. Two styles are supported: </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>18</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>Explicit termination of an array value with Default_Terminator
(a special terminator value);</LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>19</FONT></DIV>
<UL Class="Bulleted" Style="margin-bottom: 0.7em"><LI TYPE=DISC>Programmer-managed length, with Default_Terminator treated
simply as a data element. </LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>20</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> Value(Ref : <B>in</B> Pointer;<BR>
Terminator : <B>in</B> Element := Default_Terminator)<BR>
<B>return</B> Element_Array;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>21</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">This function
returns an Element_Array whose value is the array pointed to by Ref,
up to and including the first Terminator; the lower bound of the array
is Index'First. Interfaces.C.Strings.Dereference_Error is propagated
if Ref is <B>null</B>.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>22</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> Value(Ref : <B>in</B> Pointer;<BR>
Length : <B>in</B> ptrdiff_t)<BR>
<B>return</B> Element_Array;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>23</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">This function
returns an Element_Array comprising the first Length elements pointed
to by Ref. The exception Interfaces.C.Strings.Dereference_Error is propagated
if Ref is <B>null</B>. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>24</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.9em"> The "+"
and "-" functions perform arithmetic on Pointer values, based
on the Size of the array elements. In each of these functions, Pointer_Error
is propagated if a Pointer parameter is <B>null</B>. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>25</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Increment (Ref : <B>in</B> <B>out</B> Pointer);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>26</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">Equivalent to
Ref := Ref+1.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>27</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Decrement (Ref : <B>in</B> <B>out</B> Pointer);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>28</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">Equivalent to
Ref := Ref-1.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>29</FONT></DIV>
<DIV Class="Examples"><TT><B>function</B> Virtual_Length (Ref : <B>in</B> Pointer;<BR>
Terminator : <B>in</B> Element := Default_Terminator)<BR>
<B>return</B> ptrdiff_t;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>30</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">Returns the number
of Elements, up to the one just before the first Terminator, in Value(Ref,
Terminator).</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>31</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Copy_Terminated_Array<BR>
(Source : <B>in</B> Pointer;<BR>
Target : <B>in</B> Pointer;<BR>
Limit : <B>in</B> ptrdiff_t := ptrdiff_t'Last;<BR>
Terminator : <B>in</B> Element := Default_Terminator);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>32</FONT></DIV>
<DIV Class="CodeIndented" Style="margin-bottom: 0.9em">This procedure
copies Value(Source, Terminator) into the array pointed to by Target;
it stops either after Terminator has been copied, or the number of elements
copied is Limit, whichever occurs first. Dereference_Error is propagated
if either Source or Target is <B>null</B>. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>32.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Ramification: </B>It is the
programmer's responsibility to ensure that elements are not copied beyond
the logical length of the target array. </FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>32.b</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Implementation Note: </B>The
implementation has to take care to check the Limit first. </FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>33</FONT></DIV>
<DIV Class="Examples"><TT><B>procedure</B> Copy_Array (Source : <B>in</B> Pointer;<BR>
Target : <B>in</B> Pointer;<BR>
Length : <B>in</B> ptrdiff_t);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>34</FONT></DIV>
<DIV Class="CodeIndented">This procedure copies the first Length elements
from the array pointed to by Source, into the array pointed to by Target.
Dereference_Error is propagated if either Source or Target is <B>null</B>.
</DIV>
<H4 ALIGN=CENTER>Erroneous Execution</H4>
<DIV Class="Paranum"><FONT SIZE=-2>35</FONT></DIV>
<DIV Class="Normal"> <A NAME="I6487"></A>It is erroneous to dereference
a Pointer that does not designate an aliased Element. </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>35.a</FONT></DIV>
<DIV Class="Annotations"><FONT SIZE=-1><B>Discussion: </B>Such a Pointer
could arise via "+", "-", Increment, or Decrement.</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>36</FONT></DIV>
<DIV Class="Normal"> <A NAME="I6488"></A>Execution of Value(Ref, Terminator)
is erroneous if Ref does not designate an aliased Element in an Element_Array
terminated by Terminator.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>37</FONT></DIV>
<DIV Class="Normal"> <A NAME="I6489"></A>Execution of Value(Ref, Length)
is erroneous if Ref does not designate an aliased Element in an Element_Array
containing at least Length Elements between the designated Element and
the end of the array, inclusive.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>38</FONT></DIV>
<DIV Class="Normal"> <A NAME="I6490"></A>Execution of Virtual_Length(Ref,
Terminator) is erroneous if Ref does not designate an aliased Element
in an Element_Array terminated by Terminator.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>39</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> <A NAME="I6491"></A>Execution
of Copy_Terminated_Array(Source, Target, Limit, Terminator) is erroneous
in either of the following situations: </DIV>
<DIV Class="Paranum"><FONT SIZE=-2>40</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>Execution of both Value(Source,Terminator) and Value(Source,Limit)
are erroneous, or</LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>41</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>Copying writes past the end of the array containing the
Element designated by Target. </LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>42</FONT></DIV>
<DIV Class="Normal"> <A NAME="I6492"></A>Execution of Copy_Array(Source,
Target, Length) is erroneous if either Value(Source, Length) is erroneous,
or copying writes past the end of the array containing the Element designated
by Target. </DIV>
<DIV Class="NotesHeader"><FONT SIZE=-1>NOTES</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>43</FONT></DIV>
<DIV Class="Notes" Style="margin-bottom: 0.4em"><FONT SIZE=-1>14 To
compose a Pointer from an Element_Array, use 'Access on the first element.
For example (assuming appropriate instantiations): </FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>44</FONT></DIV>
<DIV Class="Examples"><TT>Some_Array : Element_Array(0..5) ;<BR>
Some_Pointer : Pointer := Some_Array(0)'Access;</TT></DIV>
<H4 ALIGN=CENTER>Examples</H4>
<DIV Class="Paranum"><FONT SIZE=-2>45</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> <I>Example of Interfaces.C.Pointers:</I>
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>46</FONT></DIV>
<DIV Class="Examples"><TT><B>with</B> Interfaces.C.Pointers;<BR>
<B>with</B> Interfaces.C.Strings;<BR>
<B>procedure</B> Test_Pointers <B>is</B><BR>
<B>package</B> C <B>renames</B> Interfaces.C;<BR>
<B>package</B> Char_Ptrs <B>is</B><BR>
<B>new</B> C.Pointers (Index => C.size_t,<BR>
Element => C.char,<BR>
Element_Array => C.char_array,<BR>
Default_Terminator => C.nul);</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>47</FONT></DIV>
<DIV Class="Examples"><TT> <B>use</B> <B>type</B> Char_Ptrs.Pointer;<BR>
<B>subtype</B> Char_Star <B>is</B> Char_Ptrs.Pointer;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>48</FONT></DIV>
<DIV Class="Examples"><TT> <B>procedure</B> Strcpy (Target_Ptr, Source_Ptr : Char_Star) <B>is</B><BR>
Target_Temp_Ptr : Char_Star := Target_Ptr;<BR>
Source_Temp_Ptr : Char_Star := Source_Ptr;<BR>
Element : C.char;<BR>
<B>begin</B><BR>
<B>if</B> Target_Temp_Ptr = <B>null</B> <B>or</B> Source_Temp_Ptr = <B>null</B> <B>then</B><BR>
<B>raise</B> C.Strings.Dereference_Error;<BR>
<B>end if</B>;</TT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>49/1</FONT></DIV>
<DIV Class="Examples"><TT>{<I><A HREF="defect1.html#8652/0065">8652/0065</A></I>}
<BR>
<B>loop</B><BR>
Element := Source_Temp_Ptr.<B>all</B>;<BR>
Target_Temp_Ptr.<B>all</B> := Element;<BR>
<B>exit</B> <B>when</B> <U>C."="(Element, C.nul)</U><S>Element = C.nul</S>;<BR>
Char_Ptrs.Increment(Target_Temp_Ptr);<BR>
Char_Ptrs.Increment(Source_Temp_Ptr);<BR>
<B>end</B> <B>loop</B>;<BR>
<B>end</B> Strcpy;<BR>
<B>begin</B><BR>
...<BR>
<B>end</B> Test_Pointers;</TT></DIV>
<HR>
<P><A HREF="AA-TOC.html">Contents</A> <A HREF="AA-0-29.html">Index</A> <A HREF="AA-B-3-1.html">Previous</A> <A HREF="AA-B-4.html">Next</A> <A HREF="AA-TTL.html">Legal</A></P>
</BODY>
</HTML>
|
