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ATEXIT(3)                BSD Library Functions Manual                ATEXIT(3)

NAME
     atexit -- register a function to be called on exit

SYNOPSIS
     #include <stdlib.h>

     int
     atexit(void (*func)(void));

     int
     atexit_b(void (^block)(void));

DESCRIPTION
     The atexit() function registers the function func to be called at program exit, whether via exit(3) or
     via return from the program's main().  Functions so registered are called in reverse order; no argu-ments arguments
     ments are passed.

     The atexit_b() function is like atexit() except the callback is a block pointer instead of a function
     pointer.

           Note: The Block_copy() function (defined in <Blocks.h>) is used by atexit_b() to make a copy of
           the block, especially for the case when a stack-based block might go out of scope when the sub-routine subroutine
           routine returns.

     These callbacks must not call exit(); if it should be necessary to terminate the process while in such
     a function, the _exit(2) function should be used.  (Alternatively, the callbacks may cause abnormal
     process termination, for example by calling abort(3).)

     At least 32 callbacks can always be registered; more are allowed as long as sufficient memory can be
     allocated.

RETURN VALUES
     The atexit() and atexit_b() functions return the value 0 if successful; otherwise the value -1 is
     returned and the global variable errno is set to indicate the error.

ERRORS
     [ENOMEM]           No memory was available to add the function to the list.  The existing list of func-tions functions
                        tions is unmodified.

SEE ALSO
     exit(3)

STANDARDS
     The atexit() function conforms to ISO/IEC 9899:1990 (``ISO C90'').

BSD                              May 20, 2008                              BSD

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