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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=" 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_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>
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>
29 C++0x <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:
38 <span class="command"><strong>gcc foo.cc -lsupc++</strong></span>
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.
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
62 Users will have to provide this information.
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
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>
83 <code class="literal">-Wl,-rpath,</code><code class="filename">destdir/lib</code>
84 </p></li><li class="listitem"><p>
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
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
102 which <code class="filename">libstdc++.so</code>
103 library the system will get at runtime.
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
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="../spine.html">Home</a></td><td align="right" valign="top"> Concurrency</td></tr></table></div></body></html>