setjmp(3C)                                             setjmp(3C)



     NAME
          setjmp, longjmp - non-local goto

     SYNOPSIS
          #include <setjmp.h>

          int setjmp (env)
          jmpbuf env;

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

     DESCRIPTION
          These functions 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.  The environment type jmpbuf is defined in the
          <setjmp.h> header file.  setjmp returns the value 0.

          longjmp restores the environment saved by the last call of
          setjmp with the corresponding env argument.  After longjmp
          is completed, program execution continues as if the
          corresponding call of setjmp (which must not itself have
          returned in the interim) had just returned the value val.
          longjmp cannot cause setjmp to return the value 0.  If
          longjmp is invoked with a second argument of 0, setjmp will
          return 1.  All accessible data have values as of the time
          longjmp was called.

     SEE ALSO
          signal(3).

     WARNING
          longjmp fails if it is called when env was never primed by a
          call to setjmp or when the last such call is in a function
          which has since returned.
















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