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main()                      C Language                     main()




Introduce program's main function


A C program consists of a  set of functions, one of which must be
called main.   This function is  called from the  runtime startup
routine after the runtime environment has been initialized.

Programs can terminate in one of two ways.  The easiest is simply
to have the main  routine return.  Control returns to the runtime
startup; it closes all open file streams and otherwise cleans up,
and then returns control  to the operating system, passing it the
value returned by main as exit status.

In some situations (errors,  for example), it may be necessary to
stop a  program, and you may  not want to return  to main.  Here,
you can  use exit;  it cleans  up the debris  left by  the broken
program and returns control directly to the operating system.

A second  exit routine, called _exit,  quickly returns control to
the  operating  system  without  performing  any  cleanup.   This
routine should  be used with care,  because bypassing the cleanup
will leave files open and buffers of data in memory.

Programs compiled  by COHERENT return to  the program that called
them; if they  return from main with a value  or call exit with a
value, that value is returned to their caller.  Programs that in-
voke  other  programs  through  the  ssyysstteemm  function  check  the
returned value to see if these secondary programs terminated suc-
cessfully.

***** See Also *****

_exit, argc, argv, C language, envp, exit























COHERENT Lexicon                                           Page 1

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