SETJMP(S)                XENIX System V                 SETJMP(S)



     Name
          setjmp, longjmp - Performs a nonlocal ``goto''.

     Syntax
          #include <setjmp.h>

          int setjmp (env)
          jmp_buf env;

          void longjmp (env, val)
          jmp_buf env;
          int val;

     Description
          These routines are useful for dealing with errors and
          interrupts encountered in a low-level subroutine of a
          program.

          setjmp saves its stack environment in env for later use by
          longjmp.  It returns a value of 0.

          longjmp restores the environment saved by the last call of
          setjmp.  It then returns in such a way that execution
          continues as if the call of setjmp had just returned the
          value val to the corresponding call to setjmp.  The routine
          which calls setjmp must not itself have returned in the
          interim.  longjmp cannot return a value of 0.  If longjmp is
          invoked with a second argument of 0, it will return a value
          of 1.  All accessible data have values as of the time
          longjmp was called. The only exception to this is register
          variables.  The value of register variables is undefined in
          the routine that called setjmp when the corresponding
          longjmp is invoked.

     See Also
          signal(S)

     Warning
          If longjmp is called even though env was never primed by a
          call to setjmp, or when the last such call was in a function
          which has since returned, absolute chaos is guaranteed.














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