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

   1 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
   2 <!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>Linking</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_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 width="20%" align="left"><a accesskey="p" href="using_namespaces.html">Prev</a> </td><th width="60%" align="center">Chapter 3. Using</th><td width="20%" align="right"> <a accesskey="n" href="using_concurrency.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.linkage"></a>Linking</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.linkage.freestanding"></a>Almost Nothing</h3></div></div></div><p>
   3         Or as close as it gets: freestanding. This is a minimal
   4         configuration, with only partial support for the standard
   5         library. Assume only the following header files can be used:
   6       </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
   7             <code class="filename">cstdarg</code>
   8           </p></li><li class="listitem"><p>
   9           <code class="filename">cstddef</code>
  10           </p></li><li class="listitem"><p>
  11           <code class="filename">cstdlib</code>
  12           </p></li><li class="listitem"><p>
  13           <code class="filename">exception</code>
  14           </p></li><li class="listitem"><p>
  15           <code class="filename">limits</code>
  16           </p></li><li class="listitem"><p>
  17           <code class="filename">new</code>
  18           </p></li><li class="listitem"><p>
  19           <code class="filename">exception</code>
  20           </p></li><li class="listitem"><p>
  21           <code class="filename">typeinfo</code>
  22           </p></li></ul></div><p>
  23         In addition, throw in
  24       </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
  25           <code class="filename">cxxabi.h</code>.
  26           </p></li></ul></div><p>
  27         In the
  28         C++11 <a class="link" href="using.html#manual.intro.using.flags" title="Command Options">dialect</a> add
  29       </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
  30           <code class="filename">initializer_list</code>
  31           </p></li><li class="listitem"><p>
  32           <code class="filename">type_traits</code>
  33           </p></li></ul></div><p> There exists a library that offers runtime support for
  34         just these headers, and it is called
  35         <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:
  36       </p><p>
  37         <span class="command"><strong>gcc foo.cc -lsupc++</strong></span>
  38       </p><p>
  39         No attempt is made to verify that only the minimal subset
  40         identified above is actually used at compile time. Violations
  41         are diagnosed as undefined symbols at link time.
  42       </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="manual.intro.using.linkage.dynamic"></a>Finding Dynamic or Shared Libraries</h3></div></div></div><p>
  43       If the only library built is the static library
  44       (<code class="filename">libstdc++.a</code>), or if
  45       specifying static linking, this section is can be skipped.  But
  46       if building or using a shared library
  47       (<code class="filename">libstdc++.so</code>), then
  48       additional location information will need to be provided.
  49     </p><p>
  50       But how?
  51     </p><p>
  52 A quick read of the relevant part of the GCC
  53       manual, <a class="link" href="http://gcc.gnu.org/onlinedocs/gcc/Invoking-G_002b_002b.html#Invoking-G_002b_002b" target="_top">Compiling
  54       C++ Programs</a>, specifies linking against a C++
  55       library. More details from the
  56       GCC <a class="link" href="http://gcc.gnu.org/faq.html#rpath" target="_top">FAQ</a>,
  57       which states <span class="emphasis"><em>GCC does not, by default, specify a
  58       location so that the dynamic linker can find dynamic libraries at
  59       runtime.</em></span>
  60     </p><p>
  61       Users will have to provide this information.
  62     </p><p>
  63       Methods vary for different platforms and different styles, and
  64       are printed to the screen during installation. To summarize:
  65     </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
  66           At runtime set <code class="literal">LD_LIBRARY_PATH</code> in your
  67           environment correctly, so that the shared library for
  68           libstdc++ can be found and loaded.  Be certain that you
  69           understand all of the other implications and behavior
  70           of <code class="literal">LD_LIBRARY_PATH</code> first.
  71         </p></li><li class="listitem"><p>
  72           Compile the path to find the library at runtime into the
  73           program.  This can be done by passing certain options to
  74           <span class="command"><strong>g++</strong></span>, which will in turn pass them on to
  75           the linker.  The exact format of the options is dependent on
  76           which linker you use:
  77         </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: circle; "><li class="listitem"><p>
  78               GNU ld (default on GNU/Linux):
  79               <code class="literal">-Wl,-rpath,</code><code class="filename">destdir/lib</code>
  80             </p></li><li class="listitem"><p>
  81             Solaris ld:
  82             <code class="literal">-Wl,-R</code><code class="filename">destdir/lib</code>
  83           </p></li></ul></div></li><li class="listitem"><p>
  84           Some linkers allow you to specify the path to the library by
  85           setting <code class="literal">LD_RUN_PATH</code> in your environment
  86           when linking.
  87         </p></li><li class="listitem"><p>
  88           On some platforms the system administrator can configure the
  89           dynamic linker to always look for libraries in
  90           <code class="filename">destdir/lib</code>, for example
  91           by using the <span class="command"><strong>ldconfig</strong></span> utility on GNU/Linux
  92           or the <span class="command"><strong>crle</strong></span> utility on Solaris. This is a
  93           system-wide change which can make the system unusable so if you
  94           are unsure then use one of the other methods described above.
  95         </p></li></ul></div><p>
  96       Use the <span class="command"><strong>ldd</strong></span> utility on the linked executable
  97       to show
  98       which <code class="filename">libstdc++.so</code>
  99       library the system will get at runtime.
 100     </p><p>
 101       A <code class="filename">libstdc++.la</code> file is
 102       also installed, for use with Libtool.  If you use Libtool to
 103       create your executables, these details are taken care of for
 104       you.
 105     </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="using_namespaces.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_concurrency.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Namespaces </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Concurrency</td></tr></table></div></body></html>