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<h1 class="settitle">The GNU C Library</h1>
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<h2 class="chapter">1 Introduction</h2>

<!-- %MENU% Purpose of the GNU C Library -->
<p>The C language provides no built-in facilities for performing such
common operations as input/output, memory management, string
manipulation, and the like.  Instead, these facilities are defined
in a standard <dfn>library</dfn>, which you compile and link with your
programs. 
<a name="index-library-1"></a>
The GNU C library, described in this document, defines all of the
library functions that are specified by the ISO&nbsp;C<!-- /@w --> standard, as well as
additional features specific to POSIX and other derivatives of the Unix
operating system, and extensions specific to the GNU system.

   <p>The purpose of this manual is to tell you how to use the facilities
of the GNU library.  We have mentioned which features belong to which
standards to help you identify things that are potentially non-portable
to other systems.  But the emphasis in this manual is not on strict
portability.

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<li><a accesskey="1" href="Getting-Started.html#Getting-Started">Getting Started</a>:              What this manual is for and how to use it. 
<li><a accesskey="2" href="Standards-and-Portability.html#Standards-and-Portability">Standards and Portability</a>:    Standards and sources upon which the GNU
                                 C library is based. 
<li><a accesskey="3" href="Using-the-Library.html#Using-the-Library">Using the Library</a>:            Some practical uses for the library. 
<li><a accesskey="4" href="Roadmap-to-the-Manual.html#Roadmap-to-the-Manual">Roadmap to the Manual</a>:        Overview of the remaining chapters in
                                 this manual. 
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