libstdc++-v3/doc/html/manual/using_dynamic_or_shared.html

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   3 <html xmlns="http://www.w3.org/1999/xhtml"><head><title>Linking</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.76.1"/><meta name="keywords" content="&#10;      ISO C++&#10;    , &#10;      library&#10;    "/><meta name="keywords" content="&#10;      ISO C++&#10;    , &#10;      runtime&#10;    , &#10;      library&#10;    "/><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_namespaces.html" title="Namespaces"/><link rel="next" href="using_concurrency.html" title="Concurrency"/></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Linking</th></tr><tr><td align="left"><a accesskey="p" href="using_namespaces.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td align="right"> <a accesskey="n" href="using_concurrency.html">Next</a></td></tr></table><hr/></div><div class="section" title="Linking"><div class="titlepage"><div><div><h2 class="title"><a id="manual.intro.using.linkage"/>Linking</h2></div></div></div><div class="section" title="Almost Nothing"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.linkage.freestanding"/>Almost Nothing</h3></div></div></div><p>
   4         Or as close as it gets: freestanding. This is a minimal
   5         configuration, with only partial support for the standard
   6         library. Assume only the following header files can be used:
   7       </p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
   8             <code class="filename">cstdarg</code>
   9           </p></li><li class="listitem"><p>
  10           <code class="filename">cstddef</code>
  11           </p></li><li class="listitem"><p>
  12           <code class="filename">cstdlib</code>
  13           </p></li><li class="listitem"><p>
  14           <code class="filename">exception</code>
  15           </p></li><li class="listitem"><p>
  16           <code class="filename">limits</code>
  17           </p></li><li class="listitem"><p>
  18           <code class="filename">new</code>
  19           </p></li><li class="listitem"><p>
  20           <code class="filename">exception</code>
  21           </p></li><li class="listitem"><p>
  22           <code class="filename">typeinfo</code>
  23           </p></li></ul></div><p>
  24         In addition, throw in
  25       </p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
  26           <code class="filename">cxxabi.h</code>.
  27           </p></li></ul></div><p>
  28         In the
  29         C++11 <a class="link" href="using.html#manual.intro.using.flags" title="Command Options">dialect</a> add
  30       </p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
  31           <code class="filename">initializer_list</code>
  32           </p></li><li class="listitem"><p>
  33           <code class="filename">type_traits</code>
  34           </p></li></ul></div><p> There exists a library that offers runtime support for
  35         just these headers, and it is called
  36         <code class="filename">libsupc++.a</code>. To use it, compile with <span class="command"><strong>gcc</strong></span> instead of <span class="command"><strong>g++</strong></span>, like so:
  37       </p><p>
  38         <span class="command"><strong>gcc foo.cc -lsupc++</strong></span>
  39       </p><p>
  40         No attempt is made to verify that only the minimal subset
  41         identified above is actually used at compile time. Violations
  42         are diagnosed as undefined symbols at link time.
  43       </p></div><div class="section" title="Finding Dynamic or Shared Libraries"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.linkage.dynamic"/>Finding Dynamic or Shared Libraries</h3></div></div></div><p>
  44       If the only library built is the static library
  45       (<code class="filename">libstdc++.a</code>), or if
  46       specifying static linking, this section is can be skipped.  But
  47       if building or using a shared library
  48       (<code class="filename">libstdc++.so</code>), then
  49       additional location information will need to be provided.
  50     </p><p>
  51       But how?
  52     </p><p>
  53 A quick read of the relevant part of the GCC
  54       manual, <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/Invoking-G_002b_002b.html#Invoking-G_002b_002b">Compiling
  55       C++ Programs</a>, specifies linking against a C++
  56       library. More details from the
  57       GCC <a class="link" href="http://gcc.gnu.org/faq.html#rpath">FAQ</a>,
  58       which states <span class="emphasis"><em>GCC does not, by default, specify a
  59       location so that the dynamic linker can find dynamic libraries at
  60       runtime.</em></span>
  61     </p><p>
  62       Users will have to provide this information.
  63     </p><p>
  64       Methods vary for different platforms and different styles, and
  65       are printed to the screen during installation. To summarize:
  66     </p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
  67           At runtime set <code class="literal">LD_LIBRARY_PATH</code> in your
  68           environment correctly, so that the shared library for
  69           libstdc++ can be found and loaded.  Be certain that you
  70           understand all of the other implications and behavior
  71           of <code class="literal">LD_LIBRARY_PATH</code> first.
  72         </p></li><li class="listitem"><p>
  73           Compile the path to find the library at runtime into the
  74           program.  This can be done by passing certain options to
  75           <span class="command"><strong>g++</strong></span>, which will in turn pass them on to
  76           the linker.  The exact format of the options is dependent on
  77           which linker you use:
  78         </p><div class="itemizedlist"><ul class="itemizedlist"><li class="listitem"><p>
  79               GNU ld (default on Linux):
  80               <code class="literal">-Wl,-rpath,</code><code class="filename">destdir/lib</code>
  81             </p></li><li class="listitem"><p>
  82               IRIX ld:
  83               <code class="literal">-Wl,-rpath,</code><code class="filename">destdir/lib</code>
  84             </p></li><li class="listitem"><p>
  85             Solaris ld:
  86             <code class="literal">-Wl,-R</code><code class="filename">destdir/lib</code>
  87           </p></li></ul></div></li><li class="listitem"><p>
  88           Some linkers allow you to specify the path to the library by
  89           setting <code class="literal">LD_RUN_PATH</code> in your environment
  90           when linking.
  91         </p></li><li class="listitem"><p>
  92           On some platforms the system administrator can configure the
  93           dynamic linker to always look for libraries in
  94           <code class="filename">destdir/lib</code>, for example
  95           by using the <span class="command"><strong>ldconfig</strong></span> utility on Linux
  96           or the <span class="command"><strong>crle</strong></span> utility on Solaris. This is a
  97           system-wide change which can make the system unusable so if you
  98           are unsure then use one of the other methods described above.
  99         </p></li></ul></div><p>
 100       Use the <span class="command"><strong>ldd</strong></span> utility on the linked executable
 101       to show
 102       which <code class="filename">libstdc++.so</code>
 103       library the system will get at runtime.
 104     </p><p>
 105       A <code class="filename">libstdc++.la</code> file is
 106       also installed, for use with Libtool.  If you use Libtool to
 107       create your executables, these details are taken care of for
 108       you.
 109     </p></div></div><div class="navfooter"><hr/><table width="100%" summary="Navigation footer"><tr><td align="left"><a accesskey="p" href="using_namespaces.html">Prev</a> </td><td align="center"><a accesskey="u" href="using.html">Up</a></td><td align="right"> <a accesskey="n" href="using_concurrency.html">Next</a></td></tr><tr><td align="left" valign="top">Namespaces </td><td align="center"><a accesskey="h" href="../index.html">Home</a></td><td align="right" valign="top"> Concurrency</td></tr></table></div></body></html>