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| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Macros</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.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 width="20%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_namespaces.html">Next</a></td></tr></table><hr /></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="manual.intro.using.macros"></a>Macros</h2></div></div></div><p> |
| All library macros begin with <code class="code">_GLIBCXX_</code>. |
| </p><p> |
| Furthermore, all pre-processor macros, switches, and |
| configuration options are gathered in the |
| file <code class="filename">c++config.h</code>, which |
| is generated during the libstdc++ configuration and build |
| process. This file is then included when needed by files part of |
| the public libstdc++ API, like <ios>. Most of these macros |
| should not be used by consumers of libstdc++, and are reserved |
| for internal implementation use. <span class="emphasis"><em>These macros cannot |
| be redefined</em></span>. |
| </p><p> |
| A select handful of macros control libstdc++ extensions and extra |
| features, or provide versioning information for the API. Only |
| those macros listed below are offered for consideration by the |
| general public. |
| </p><p>Below is the macro which users may check for library version |
| information. </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">__GLIBCXX__</code></span></dt><dd><p>The current version of |
| libstdc++ in compressed ISO date format, form of an unsigned |
| long. For details on the value of this particular macro for a |
| particular release, please consult this <a class="link" href="abi.html" title="ABI Policy and Guidelines"> |
| document</a>. |
| </p></dd></dl></div><p>Below are the macros which users may change with #define/#undef or |
| with -D/-U compiler flags. The default state of the symbol is |
| listed.</p><p><span class="quote">“<span class="quote">Configurable</span>”</span> (or <span class="quote">“<span class="quote">Not configurable</span>”</span>) means |
| that the symbol is initially chosen (or not) based on |
| --enable/--disable options at library build and configure time |
| (documented <a class="link" href="configure.html" title="Configure">here</a>), with the |
| various --enable/--disable choices being translated to |
| #define/#undef). |
| </p><p> <acronym class="acronym">ABI</acronym> means that changing from the default value may |
| mean changing the <acronym class="acronym">ABI</acronym> of compiled code. In other words, these |
| choices control code which has already been compiled (i.e., in a |
| binary such as libstdc++.a/.so). If you explicitly #define or |
| #undef these macros, the <span class="emphasis"><em>headers</em></span> may see different code |
| paths, but the <span class="emphasis"><em>libraries</em></span> which you link against will not. |
| Experimenting with different values with the expectation of |
| consistent linkage requires changing the config headers before |
| building/installing the library. |
| </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="code">_GLIBCXX_USE_DEPRECATED</code></span></dt><dd><p> |
| Defined by default. Not configurable. ABI-changing. Turning this off |
| removes older ARM-style iostreams code, and other anachronisms |
| from the API. This macro is dependent on the version of the |
| standard being tracked, and as a result may give different results for |
| <code class="code">-std=c++98</code> and <code class="code">-std=c++11</code>. This may |
| be useful in updating old C++ code which no longer meet the |
| requirements of the language, or for checking current code |
| against new language standards. |
| </p></dd><dt><span class="term"><code class="code">_GLIBCXX_CONCEPT_CHECKS</code></span></dt><dd><p> |
| Undefined by default. Configurable via |
| <code class="code">--enable-concept-checks</code>. When defined, performs |
| compile-time checking on certain template instantiations to |
| detect violations of the requirements of the standard. This |
| is described in more detail <a class="link" href="ext_compile_checks.html" title="Chapter 16. Compile Time Checks">here</a>. |
| </p></dd><dt><span class="term"><code class="code">_GLIBCXX_DEBUG</code></span></dt><dd><p> |
| Undefined by default. When defined, compiles user code using |
| the <a class="link" href="debug_mode.html" title="Chapter 17. Debug Mode">debug mode</a>. |
| </p></dd><dt><span class="term"><code class="code">_GLIBCXX_DEBUG_PEDANTIC</code></span></dt><dd><p> |
| Undefined by default. When defined while compiling with |
| the <a class="link" href="debug_mode.html" title="Chapter 17. Debug Mode">debug mode</a>, makes |
| the debug mode extremely picky by making the use of libstdc++ |
| extensions and libstdc++-specific behavior into errors. |
| </p></dd><dt><span class="term"><code class="code">_GLIBCXX_PARALLEL</code></span></dt><dd><p>Undefined by default. When defined, compiles user code |
| using the <a class="link" href="parallel_mode.html" title="Chapter 18. Parallel Mode">parallel |
| mode</a>. |
| </p></dd><dt><span class="term"><code class="code">_GLIBCXX_PROFILE</code></span></dt><dd><p>Undefined by default. When defined, compiles user code |
| using the <a class="link" href="profile_mode.html" title="Chapter 19. Profile Mode">profile |
| mode</a>. |
| </p></dd></dl></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_headers.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="using.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="using_namespaces.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Headers </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Namespaces</td></tr></table></div></body></html> |
