hc
2023-11-06 15ade055295d13f95d49e3d99b09f3bbfb4a43e7
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
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 1987-2016 Free Software Foundation, Inc.
 
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation.  A copy of
the license is included in the
section entitled "GNU Free Documentation License".
 
This manual contains no Invariant Sections.  The Front-Cover Texts are
(a) (see below), and the Back-Cover Texts are (b) (see below).
 
(a) The FSF's Front-Cover Text is:
 
A GNU Manual
 
(b) The FSF's Back-Cover Text is:
 
You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development. -->
<!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ -->
<head>
<title>The C Preprocessor: Top</title>
 
<meta name="description" content="The C Preprocessor: Top">
<meta name="keywords" content="The C Preprocessor: Top">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="#Top" rel="start" title="Top">
<link href="Index-of-Directives.html#Index-of-Directives" rel="index" title="Index of Directives">
<link href="#SEC_Contents" rel="contents" title="Table of Contents">
<link href="../dir/index.html" rel="up" title="(dir)">
<link href="Overview.html#Overview" rel="next" title="Overview">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {margin-left: 3.2em}
kbd {font-style:oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>
 
 
</head>
 
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<h1 class="settitle" align="center">The C Preprocessor</h1>
 
 
 
 
 
 
 
 
 
 
 
 
<a name="SEC_Contents"></a>
<h2 class="contents-heading">Table of Contents</h2>
 
<div class="contents">
 
<ul class="no-bullet">
  <li><a name="toc-Overview-1" href="Overview.html#Overview">1 Overview</a>
  <ul class="no-bullet">
    <li><a name="toc-Character-sets-1" href="Character-sets.html#Character-sets">1.1 Character sets</a></li>
    <li><a name="toc-Initial-processing-1" href="Initial-processing.html#Initial-processing">1.2 Initial processing</a></li>
    <li><a name="toc-Tokenization-1" href="Tokenization.html#Tokenization">1.3 Tokenization</a></li>
    <li><a name="toc-The-preprocessing-language-1" href="The-preprocessing-language.html#The-preprocessing-language">1.4 The preprocessing language</a></li>
  </ul></li>
  <li><a name="toc-Header-Files-1" href="Header-Files.html#Header-Files">2 Header Files</a>
  <ul class="no-bullet">
    <li><a name="toc-Include-Syntax-1" href="Include-Syntax.html#Include-Syntax">2.1 Include Syntax</a></li>
    <li><a name="toc-Include-Operation-1" href="Include-Operation.html#Include-Operation">2.2 Include Operation</a></li>
    <li><a name="toc-Search-Path-1" href="Search-Path.html#Search-Path">2.3 Search Path</a></li>
    <li><a name="toc-Once_002dOnly-Headers-1" href="Once_002dOnly-Headers.html#Once_002dOnly-Headers">2.4 Once-Only Headers</a></li>
    <li><a name="toc-Alternatives-to-Wrapper-_0023ifndef-1" href="Alternatives-to-Wrapper-_0023ifndef.html#Alternatives-to-Wrapper-_0023ifndef">2.5 Alternatives to Wrapper #ifndef</a></li>
    <li><a name="toc-Computed-Includes-1" href="Computed-Includes.html#Computed-Includes">2.6 Computed Includes</a></li>
    <li><a name="toc-Wrapper-Headers-1" href="Wrapper-Headers.html#Wrapper-Headers">2.7 Wrapper Headers</a></li>
    <li><a name="toc-System-Headers-1" href="System-Headers.html#System-Headers">2.8 System Headers</a></li>
  </ul></li>
  <li><a name="toc-Macros-1" href="Macros.html#Macros">3 Macros</a>
  <ul class="no-bullet">
    <li><a name="toc-Object_002dlike-Macros-1" href="Object_002dlike-Macros.html#Object_002dlike-Macros">3.1 Object-like Macros</a></li>
    <li><a name="toc-Function_002dlike-Macros-1" href="Function_002dlike-Macros.html#Function_002dlike-Macros">3.2 Function-like Macros</a></li>
    <li><a name="toc-Macro-Arguments-1" href="Macro-Arguments.html#Macro-Arguments">3.3 Macro Arguments</a></li>
    <li><a name="toc-Stringification-1" href="Stringification.html#Stringification">3.4 Stringification</a></li>
    <li><a name="toc-Concatenation-1" href="Concatenation.html#Concatenation">3.5 Concatenation</a></li>
    <li><a name="toc-Variadic-Macros-1" href="Variadic-Macros.html#Variadic-Macros">3.6 Variadic Macros</a></li>
    <li><a name="toc-Predefined-Macros-1" href="Predefined-Macros.html#Predefined-Macros">3.7 Predefined Macros</a>
    <ul class="no-bullet">
      <li><a name="toc-Standard-Predefined-Macros-1" href="Standard-Predefined-Macros.html#Standard-Predefined-Macros">3.7.1 Standard Predefined Macros</a></li>
      <li><a name="toc-Common-Predefined-Macros-1" href="Common-Predefined-Macros.html#Common-Predefined-Macros">3.7.2 Common Predefined Macros</a></li>
      <li><a name="toc-System_002dspecific-Predefined-Macros-1" href="System_002dspecific-Predefined-Macros.html#System_002dspecific-Predefined-Macros">3.7.3 System-specific Predefined Macros</a></li>
      <li><a name="toc-C_002b_002b-Named-Operators-1" href="C_002b_002b-Named-Operators.html#C_002b_002b-Named-Operators">3.7.4 C++ Named Operators</a></li>
    </ul></li>
    <li><a name="toc-Undefining-and-Redefining-Macros-1" href="Undefining-and-Redefining-Macros.html#Undefining-and-Redefining-Macros">3.8 Undefining and Redefining Macros</a></li>
    <li><a name="toc-Directives-Within-Macro-Arguments-1" href="Directives-Within-Macro-Arguments.html#Directives-Within-Macro-Arguments">3.9 Directives Within Macro Arguments</a></li>
    <li><a name="toc-Macro-Pitfalls-1" href="Macro-Pitfalls.html#Macro-Pitfalls">3.10 Macro Pitfalls</a>
    <ul class="no-bullet">
      <li><a name="toc-Misnesting-1" href="Misnesting.html#Misnesting">3.10.1 Misnesting</a></li>
      <li><a name="toc-Operator-Precedence-Problems-1" href="Operator-Precedence-Problems.html#Operator-Precedence-Problems">3.10.2 Operator Precedence Problems</a></li>
      <li><a name="toc-Swallowing-the-Semicolon-1" href="Swallowing-the-Semicolon.html#Swallowing-the-Semicolon">3.10.3 Swallowing the Semicolon</a></li>
      <li><a name="toc-Duplication-of-Side-Effects-1" href="Duplication-of-Side-Effects.html#Duplication-of-Side-Effects">3.10.4 Duplication of Side Effects</a></li>
      <li><a name="toc-Self_002dReferential-Macros-1" href="Self_002dReferential-Macros.html#Self_002dReferential-Macros">3.10.5 Self-Referential Macros</a></li>
      <li><a name="toc-Argument-Prescan-1" href="Argument-Prescan.html#Argument-Prescan">3.10.6 Argument Prescan</a></li>
      <li><a name="toc-Newlines-in-Arguments-1" href="Newlines-in-Arguments.html#Newlines-in-Arguments">3.10.7 Newlines in Arguments</a></li>
    </ul></li>
  </ul></li>
  <li><a name="toc-Conditionals-1" href="Conditionals.html#Conditionals">4 Conditionals</a>
  <ul class="no-bullet">
    <li><a name="toc-Conditional-Uses-1" href="Conditional-Uses.html#Conditional-Uses">4.1 Conditional Uses</a></li>
    <li><a name="toc-Conditional-Syntax-1" href="Conditional-Syntax.html#Conditional-Syntax">4.2 Conditional Syntax</a>
    <ul class="no-bullet">
      <li><a name="toc-Ifdef-1" href="Ifdef.html#Ifdef">4.2.1 Ifdef</a></li>
      <li><a name="toc-If-1" href="If.html#If">4.2.2 If</a></li>
      <li><a name="toc-Defined-1" href="Defined.html#Defined">4.2.3 Defined</a></li>
      <li><a name="toc-Else-1" href="Else.html#Else">4.2.4 Else</a></li>
      <li><a name="toc-Elif-1" href="Elif.html#Elif">4.2.5 Elif</a></li>
    </ul></li>
    <li><a name="toc-Deleted-Code-1" href="Deleted-Code.html#Deleted-Code">4.3 Deleted Code</a></li>
  </ul></li>
  <li><a name="toc-Diagnostics-1" href="Diagnostics.html#Diagnostics">5 Diagnostics</a></li>
  <li><a name="toc-Line-Control-1" href="Line-Control.html#Line-Control">6 Line Control</a></li>
  <li><a name="toc-Pragmas-1" href="Pragmas.html#Pragmas">7 Pragmas</a></li>
  <li><a name="toc-Other-Directives-1" href="Other-Directives.html#Other-Directives">8 Other Directives</a></li>
  <li><a name="toc-Preprocessor-Output-1" href="Preprocessor-Output.html#Preprocessor-Output">9 Preprocessor Output</a></li>
  <li><a name="toc-Traditional-Mode-1" href="Traditional-Mode.html#Traditional-Mode">10 Traditional Mode</a>
  <ul class="no-bullet">
    <li><a name="toc-Traditional-lexical-analysis-1" href="Traditional-lexical-analysis.html#Traditional-lexical-analysis">10.1 Traditional lexical analysis</a></li>
    <li><a name="toc-Traditional-macros-1" href="Traditional-macros.html#Traditional-macros">10.2 Traditional macros</a></li>
    <li><a name="toc-Traditional-miscellany-1" href="Traditional-miscellany.html#Traditional-miscellany">10.3 Traditional miscellany</a></li>
    <li><a name="toc-Traditional-warnings-1" href="Traditional-warnings.html#Traditional-warnings">10.4 Traditional warnings</a></li>
  </ul></li>
  <li><a name="toc-Implementation-Details-1" href="Implementation-Details.html#Implementation-Details">11 Implementation Details</a>
  <ul class="no-bullet">
    <li><a name="toc-Implementation_002ddefined-behavior-1" href="Implementation_002ddefined-behavior.html#Implementation_002ddefined-behavior">11.1 Implementation-defined behavior</a></li>
    <li><a name="toc-Implementation-limits-1" href="Implementation-limits.html#Implementation-limits">11.2 Implementation limits</a></li>
    <li><a name="toc-Obsolete-Features-1" href="Obsolete-Features.html#Obsolete-Features">11.3 Obsolete Features</a>
    <ul class="no-bullet">
      <li><a name="toc-Assertions" href="Obsolete-Features.html#Assertions">11.3.1 Assertions</a></li>
    </ul></li>
    <li><a name="toc-Differences-from-previous-versions-1" href="Differences-from-previous-versions.html#Differences-from-previous-versions">11.4 Differences from previous versions</a></li>
  </ul></li>
  <li><a name="toc-Invocation-1" href="Invocation.html#Invocation">12 Invocation</a></li>
  <li><a name="toc-Environment-Variables-1" href="Environment-Variables.html#Environment-Variables">13 Environment Variables</a></li>
  <li><a name="toc-GNU-Free-Documentation-License-1" href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License">GNU Free Documentation License</a>
  <ul class="no-bullet">
    <li><a name="toc-ADDENDUM_003a-How-to-use-this-License-for-your-documents" href="GNU-Free-Documentation-License.html#ADDENDUM_003a-How-to-use-this-License-for-your-documents">ADDENDUM: How to use this License for your documents</a></li>
  </ul></li>
  <li><a name="toc-Index-of-Directives-1" href="Index-of-Directives.html#Index-of-Directives">Index of Directives</a></li>
  <li><a name="toc-Option-Index-1" href="Option-Index.html#Option-Index">Option Index</a></li>
  <li><a name="toc-Concept-Index-1" href="Concept-Index.html#Concept-Index">Concept Index</a></li>
</ul>
</div>
 
 
<a name="Top"></a>
<div class="header">
<p>
Next: <a href="Overview.html#Overview" accesskey="n" rel="next">Overview</a>, Up: <a href="../dir/index.html" accesskey="u" rel="up">(dir)</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="SEC_Top"></a>
<p>The C preprocessor implements the macro language used to transform C,
C++, and Objective-C programs before they are compiled.  It can also be
useful on its own.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="Overview.html#Overview" accesskey="1">Overview</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Header-Files.html#Header-Files" accesskey="2">Header Files</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Macros.html#Macros" accesskey="3">Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Conditionals.html#Conditionals" accesskey="4">Conditionals</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Diagnostics.html#Diagnostics" accesskey="5">Diagnostics</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Line-Control.html#Line-Control" accesskey="6">Line Control</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Pragmas.html#Pragmas" accesskey="7">Pragmas</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Other-Directives.html#Other-Directives" accesskey="8">Other Directives</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Preprocessor-Output.html#Preprocessor-Output" accesskey="9">Preprocessor Output</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Traditional-Mode.html#Traditional-Mode">Traditional Mode</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Implementation-Details.html#Implementation-Details">Implementation Details</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Invocation.html#Invocation">Invocation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Environment-Variables.html#Environment-Variables">Environment Variables</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="GNU-Free-Documentation-License.html#GNU-Free-Documentation-License">GNU Free Documentation License</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Index-of-Directives.html#Index-of-Directives">Index of Directives</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Option-Index.html#Option-Index">Option Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Concept-Index.html#Concept-Index">Concept Index</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
</pre></th></tr><tr><th colspan="3" align="left" valign="top"><pre class="menu-comment"> &mdash; The Detailed Node Listing &mdash;
 
Overview
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Character-sets.html#Character-sets">Character sets</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Initial-processing.html#Initial-processing">Initial processing</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Tokenization.html#Tokenization">Tokenization</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="The-preprocessing-language.html#The-preprocessing-language">The preprocessing language</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Header Files
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Include-Syntax.html#Include-Syntax">Include Syntax</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Include-Operation.html#Include-Operation">Include Operation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Search-Path.html#Search-Path">Search Path</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Once_002dOnly-Headers.html#Once_002dOnly-Headers">Once-Only Headers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Alternatives-to-Wrapper-_0023ifndef.html#Alternatives-to-Wrapper-_0023ifndef">Alternatives to Wrapper #ifndef</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Computed-Includes.html#Computed-Includes">Computed Includes</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Wrapper-Headers.html#Wrapper-Headers">Wrapper Headers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="System-Headers.html#System-Headers">System Headers</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Macros
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Object_002dlike-Macros.html#Object_002dlike-Macros">Object-like Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Function_002dlike-Macros.html#Function_002dlike-Macros">Function-like Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Macro-Arguments.html#Macro-Arguments">Macro Arguments</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Stringification.html#Stringification">Stringification</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Concatenation.html#Concatenation">Concatenation</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Variadic-Macros.html#Variadic-Macros">Variadic Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Predefined-Macros.html#Predefined-Macros">Predefined Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Undefining-and-Redefining-Macros.html#Undefining-and-Redefining-Macros">Undefining and Redefining Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Directives-Within-Macro-Arguments.html#Directives-Within-Macro-Arguments">Directives Within Macro Arguments</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Macro-Pitfalls.html#Macro-Pitfalls">Macro Pitfalls</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Predefined Macros
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Standard-Predefined-Macros.html#Standard-Predefined-Macros">Standard Predefined Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Common-Predefined-Macros.html#Common-Predefined-Macros">Common Predefined Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="System_002dspecific-Predefined-Macros.html#System_002dspecific-Predefined-Macros">System-specific Predefined Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="C_002b_002b-Named-Operators.html#C_002b_002b-Named-Operators">C++ Named Operators</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Macro Pitfalls
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Misnesting.html#Misnesting">Misnesting</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Operator-Precedence-Problems.html#Operator-Precedence-Problems">Operator Precedence Problems</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Swallowing-the-Semicolon.html#Swallowing-the-Semicolon">Swallowing the Semicolon</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Duplication-of-Side-Effects.html#Duplication-of-Side-Effects">Duplication of Side Effects</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Self_002dReferential-Macros.html#Self_002dReferential-Macros">Self-Referential Macros</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Argument-Prescan.html#Argument-Prescan">Argument Prescan</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Newlines-in-Arguments.html#Newlines-in-Arguments">Newlines in Arguments</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Conditionals
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Conditional-Uses.html#Conditional-Uses">Conditional Uses</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Conditional-Syntax.html#Conditional-Syntax">Conditional Syntax</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Deleted-Code.html#Deleted-Code">Deleted Code</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Conditional Syntax
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Ifdef.html#Ifdef">Ifdef</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="If.html#If">If</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Defined.html#Defined">Defined</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Else.html#Else">Else</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Elif.html#Elif">Elif</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Implementation Details
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Implementation_002ddefined-behavior.html#Implementation_002ddefined-behavior">Implementation-defined behavior</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Implementation-limits.html#Implementation-limits">Implementation limits</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Obsolete-Features.html#Obsolete-Features">Obsolete Features</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="Differences-from-previous-versions.html#Differences-from-previous-versions">Differences from previous versions</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
Obsolete Features
 
</pre></th></tr><tr><td align="left" valign="top">&bull; <a href="Obsolete-Features.html#Obsolete-Features">Obsolete Features</a>:</td><td>&nbsp;&nbsp;</td><td align="left" valign="top">
</td></tr>
<tr><th colspan="3" align="left" valign="top"><pre class="menu-comment">
</pre></th></tr></table>
 
<p>Copyright &copy; 1987-2016 Free Software Foundation, Inc.
</p>
<p>Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation.  A copy of
the license is included in the
section entitled &ldquo;GNU Free Documentation License&rdquo;.
</p>
<p>This manual contains no Invariant Sections.  The Front-Cover Texts are
(a) (see below), and the Back-Cover Texts are (b) (see below).
</p>
<p>(a) The FSF&rsquo;s Front-Cover Text is:
</p>
<p>A GNU Manual
</p>
<p>(b) The FSF&rsquo;s Back-Cover Text is:
</p>
<p>You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development.
</p>
 
<hr>
<div class="header">
<p>
Next: <a href="Overview.html#Overview" accesskey="n" rel="next">Overview</a>, Up: <a href="../dir/index.html" accesskey="u" rel="up">(dir)</a> &nbsp; [<a href="#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index-of-Directives.html#Index-of-Directives" title="Index" rel="index">Index</a>]</p>
</div>
 
 
 
</body>
</html>