setjmp(3C) — sys5



SETJMP(3C)      DOMAIN/IX Reference Manual (SYS5)      SETJMP(3C)



NAME
     setjmp, longjmp - non-local goto

USAGE
     #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 pro-
     gram.

     Setjmp saves its stack environment in env (whose type,
     jmpbuf, is defined in the <setjmp.h> header file) for later
     use by longjmp.  It returns the value zero.

     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 zero.  If
     longjmp is invoked with a second argument of zero, setjmp
     will return 1.  All accessible data had values as of the
     time longjmp was called.

NOTES
     If env was never primed by a call to setjmp, or if the last
     such call was in a function which has since returned, and
     you call longjmp, unexpected results are likely.

RELATED INFORMATION
     signal(2)
















Printed 5/10/85                                          SETJMP-1
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