SETJMP(3P)                                          POSIX Programmer's Manual                                         SETJMP(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       setjmp - set jump point for a non-local goto

SYNOPSIS
       #include <setjmp.h>

       int setjmp(jmp_buf env);


DESCRIPTION
       A call to setjmp() shall save the calling environment in its env argument for later use by longjmp().

       It  is  unspecified whether setjmp() is a macro or a function.  If a macro definition is suppressed in order to access an
       actual function, or a program defines an external identifier with the name setjmp, the behavior is undefined.

       An application shall ensure that an invocation of setjmp() appears in one of the following contexts only:

        * The entire controlling expression of a selection or iteration statement

        * One operand of a relational or equality operator with the other operand an  integral  constant  expression,  with  the
          resulting expression being the entire controlling expression of a selection or iteration statement

        * The  operand of a unary '!' operator with the resulting expression being the entire controlling expression of a selec-
          tion or iteration

        * The entire expression of an expression statement (possibly cast to void)

       If the invocation appears in any other context, the behavior is undefined.

RETURN VALUE
       If the return is from a direct invocation, setjmp() shall return 0. If the return is from a call to  longjmp(),  setjmp()
       shall return a non-zero value.

ERRORS
       No errors are defined.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       In  general,  sigsetjmp() is more useful in dealing with errors and interrupts encountered in a low-level subroutine of a
       program.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       longjmp(), sigsetjmp(), the Base Definitions volume of IEEE Std 1003.1-2001, <setjmp.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                    SETJMP(3P)