1 <?xml version=
"1.0" encoding=
"UTF-8" standalone=
"no"?>
2 <!DOCTYPE html PUBLIC
"-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
3 <html xmlns=
"http://www.w3.org/1999/xhtml"><head><title>Macros
</title><meta name=
"generator" content=
"DocBook XSL-NS Stylesheets V1.75.2"/><meta name=
"keywords" content=
" ISO C++ , library "/><link rel=
"home" href=
"../spine.html" title=
"The GNU C++ Library"/><link rel=
"up" href=
"using.html" title=
"Chapter 3. Using"/><link rel=
"prev" href=
"using_headers.html" title=
"Headers"/><link rel=
"next" href=
"using_namespaces.html" title=
"Namespaces"/></head><body><div class=
"navheader"><table width=
"100%" summary=
"Navigation header"><tr><th colspan=
"3" align=
"center">Macros
</th></tr><tr><td align=
"left"><a accesskey=
"p" href=
"using_headers.html">Prev
</a> </td><th width=
"60%" align=
"center">Chapter
3. Using
</th><td align=
"right"> <a accesskey=
"n" href=
"using_namespaces.html">Next
</a></td></tr></table><hr/></div><div class=
"section" title=
"Macros"><div class=
"titlepage"><div><div><h2 class=
"title"><a id=
"manual.intro.using.macros"/>Macros
</h2></div></div></div><p>
4 All library macros begin with
<code class=
"code">_GLIBCXX_
</code>.
6 Furthermore, all pre-processor macros, switches, and
7 configuration options are gathered in the
8 file
<code class=
"filename">c++config.h
</code>, which
9 is generated during the libstdc++ configuration and build
10 process. This file is then included when needed by files part of
11 the public libstdc++ API, like
<ios
>. Most of these macros
12 should not be used by consumers of libstdc++, and are reserved
13 for internal implementation use.
<span class=
"emphasis"><em>These macros cannot
14 be redefined
</em></span>.
16 A select handful of macros control libstdc++ extensions and extra
17 features, or provide versioning information for the API. Only
18 those macros listed below are offered for consideration by the
20 </p><p>Below is the macro which users may check for library version
21 information.
</p><div class=
"variablelist"><dl><dt><span class=
"term"><code class=
"code">__GLIBCXX__
</code></span></dt><dd><p>The current version of
22 libstdc++ in compressed ISO date format, form of an unsigned
23 long. For details on the value of this particular macro for a
24 particular release, please consult this
<a class=
"link" href=
"abi.html" title=
"ABI Policy and Guidelines">
26 </p></dd></dl></div><p>Below are the macros which users may change with #define/#undef or
27 with -D/-U compiler flags. The default state of the symbol is
28 listed.
</p><p><span class=
"quote">“
<span class=
"quote">Configurable
</span>”
</span> (or
<span class=
"quote">“
<span class=
"quote">Not configurable
</span>”
</span>) means
29 that the symbol is initially chosen (or not) based on
30 --enable/--disable options at library build and configure time
31 (documented
<a class=
"link" href=
"configure.html" title=
"Configure">here
</a>), with the
32 various --enable/--disable choices being translated to
34 </p><p> <acronym class=
"acronym">ABI
</acronym> means that changing from the default value may
35 mean changing the
<acronym class=
"acronym">ABI
</acronym> of compiled code. In other words, these
36 choices control code which has already been compiled (i.e., in a
37 binary such as libstdc++.a/.so). If you explicitly #define or
38 #undef these macros, the
<span class=
"emphasis"><em>headers
</em></span> may see different code
39 paths, but the
<span class=
"emphasis"><em>libraries
</em></span> which you link against will not.
40 Experimenting with different values with the expectation of
41 consistent linkage requires changing the config headers before
42 building/installing the library.
43 </p><div class=
"variablelist"><dl><dt><span class=
"term"><code class=
"code">_GLIBCXX_USE_DEPRECATED
</code></span></dt><dd><p>
44 Defined by default. Not configurable. ABI-changing. Turning this off
45 removes older ARM-style iostreams code, and other anachronisms
46 from the API. This macro is dependent on the version of the
47 standard being tracked, and as a result may give different results for
48 <code class=
"code">-std=c++
98</code> and
<code class=
"code">-std=c++
0x
</code>. This may
49 be useful in updating old C++ code which no longer meet the
50 requirements of the language, or for checking current code
51 against new language standards.
52 </p></dd><dt><span class=
"term"><code class=
"code">_GLIBCXX_FORCE_NEW
</code></span></dt><dd><p>
53 Undefined by default. When defined, memory allocation and
54 allocators controlled by libstdc++ call operator new/delete
55 without caching and pooling. Configurable via
56 <code class=
"code">--enable-libstdcxx-allocator
</code>. ABI-changing.
57 </p></dd><dt><span class=
"term"><code class=
"code">_GLIBCXX_CONCEPT_CHECKS
</code></span></dt><dd><p>
58 Undefined by default. Configurable via
59 <code class=
"code">--enable-concept-checks
</code>. When defined, performs
60 compile-time checking on certain template instantiations to
61 detect violations of the requirements of the standard. This
62 is described in more detail
<a class=
"link" href=
"ext_compile_checks.html" title=
"Chapter 16. Compile Time Checks">here
</a>.
63 </p></dd><dt><span class=
"term"><code class=
"code">_GLIBCXX_DEBUG
</code></span></dt><dd><p>
64 Undefined by default. When defined, compiles user code using
65 the
<a class=
"link" href=
"debug_mode.html" title=
"Chapter 17. Debug Mode">debug mode
</a>.
66 </p></dd><dt><span class=
"term"><code class=
"code">_GLIBCXX_DEBUG_PEDANTIC
</code></span></dt><dd><p>
67 Undefined by default. When defined while compiling with
68 the
<a class=
"link" href=
"debug_mode.html" title=
"Chapter 17. Debug Mode">debug mode
</a>, makes
69 the debug mode extremely picky by making the use of libstdc++
70 extensions and libstdc++-specific behavior into errors.
71 </p></dd><dt><span class=
"term"><code class=
"code">_GLIBCXX_PARALLEL
</code></span></dt><dd><p>Undefined by default. When defined, compiles user code
72 using the
<a class=
"link" href=
"parallel_mode.html" title=
"Chapter 18. Parallel Mode">parallel
74 </p></dd><dt><span class=
"term"><code class=
"code">_GLIBCXX_PROFILE
</code></span></dt><dd><p>Undefined by default. When defined, compiles user code
75 using the
<a class=
"link" href=
"profile_mode.html" title=
"Chapter 19. Profile Mode">profile
77 </p></dd></dl></div></div><div class=
"navfooter"><hr/><table width=
"100%" summary=
"Navigation footer"><tr><td align=
"left"><a accesskey=
"p" href=
"using_headers.html">Prev
</a> </td><td align=
"center"><a accesskey=
"u" href=
"using.html">Up
</a></td><td align=
"right"> <a accesskey=
"n" href=
"using_namespaces.html">Next
</a></td></tr><tr><td align=
"left" valign=
"top">Headers
</td><td align=
"center"><a accesskey=
"h" href=
"../spine.html">Home
</a></td><td align=
"right" valign=
"top"> Namespaces
</td></tr></table></div></body></html>