INTRO(3)                             BSD                              INTRO(3)



NAME
     intro - introduction to C library functions

DESCRIPTION
     This section describes functions that can be found in various libraries.
     The library functions are those other than the functions that directly
     invoke UNIX system primitives, described in Section 2.  Most of these
     functions are accessible from the C library, libc.  The C library also
     includes all the functions described in Section 2.

     A subset of these functions is available from FORTRAN; they are described
     separately in intro(3F).

     The functions described in this section are grouped into various
     sections:

     (3)  The straight "3" functions are the standard C library functions.

     (3N) These functions constitute the internet network library.

     (3S) These functions constitute the standard"I/O"package, see stdio(3S)
          for more details.  Declarations for these functions can be obtained
          from the include file <stdio.h>.

     (3C) These routines are included for compatibility with other systems.
          In particular, a number of system call interfaces provided in
          previous releases have been included for source code compatibility.
          Use of these routines should, for the most part, be avoided.  The
          manual page entry for each compatibility routine indicates the
          proper interface to use.

     (3M) Declarations for math functions may be obtained from the include
          file <math.h>.  When one of these functions detects an error, it
          invokes matherr(3M).

     (3X) These functions constitute minor libraries and other miscellaneous
          run-time facilities.  Most are available only when programming in C.
          These functions include libraries that provide device independent
          plotting functions, terminal-independent screen management routines
          for two dimensional non-bitmap display terminals, and functions for
          managing data bases with inverted indexes.  These functions are
          located in separate libraries indicated in each manual entry.

     (3P) These functions constitute facilities for thread management, thread
          priority scheduling, synchronization primitives, thread
          cancellation, process control and thread-specific data handling.
          These functions are based on draft 4 of the IEEE P1003.4a-1990
          standard.

     (3T) These functions constitute facilities for additional thread
          manipulation.  The functions comprise a low level set of calls based
          on the Mach thread interface.  Domain/OS also supplies new calls to
          add functionality that Mach does not provide.

BUILT-IN CODE
     Domain C supports "built-in" code for the fabs, sin, cos, tan, log, exp,
     atan, atan2, and sqrt math routines and for the strcpy, strncpy, strncat,
     strcat, strcmp, strncmp, and strlen string handling routines.  <math.h>
     makes the defining of the built-in math routines conditional upon your
     defining the _MATH_BUILTINS macro, which you can do either by adding the
     line

          #define _MATH_BUILTINS

     to your program or by compiling it with the -D_MATH_BUILTINS option.
     <string.h> makes the defining of the built-in string routines conditional
     upon your defining the _STRING_BUILTINS macro, which you can do either by
     adding the line

          #define _STRING_BUILTINS

     to your program or by compiling it with the -D_STRING_BUILTINS option.
     Both _MATH_BUILTINS and _STRING_BUILTINS get defined if you define
     _BUILTINS.  <apollo/builtins.h> defines both the built-in math and string
     routines unconditionally.

     Using these built-in routines can result in much faster executables,
     particularly when double-precision math functions are used heavily.
     However, they create somewhat longer object files and do no error
     checking.  Therefore, do not use the built-in math functions if your
     programs rely on matherr(3M) error handling.

FILES
     /lib/clib
     /lib/libc   global libraries

SEE ALSO
     cc(1), ld(1), nm(1) intro(2), matherr(3M), stdio(3S), math(7).
     Domain C Language Reference.