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 fa-
cilities are defined in a standard library, which you compile and link with your programs.
The GNU C library, described in this document, defines all of the library functions that
are specified by the ISO C standard, as well as additional features specific to POSIX and
other derivatives of the Unix operating system, and extensions specific to the GNU system.
The purpose of this manual is to tell you how to use the facilities of the GNU library.
