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onjmp

Portability:

SAS/C extension

SYNOPSIS

#include <lcjmp.h>

void onjmp(jmp_buf env, int code, target);

DESCRIPTION

onjmp defines the target label as a point to which control should be transferred by a call to longjmp . The longjmp call specifies the same env value as onjmp . The integer value specified by the longjmp call is stored in the code integer.

onjmp sets the code variable to 0 on completion. Because the occurrence of a longjmp assigns onjmp a value other than 0, the value of code can be tested elsewhere to determine whether a jump has taken place.

RETURN VALUE

onjmp has no return value.

CAUTION

Variables of storage class auto and register , whose values are changed between the onjmp and longjmp calls, have indeterminate values after the branch to target unless declared volatile .

onjmp is implemented as a macro and should not be used in any position where a value is required.

PORTABILITY

onjmp is not a Standard construct; however, the macro that implements it is portable to any system that implements setjmp .

IMPLEMENTATION

onjmp is implemented as

#define onjmp(e, c, t) if (c = setjmp(e)) goto t

See setjmp for further implementation information.

EXAMPLE

#include <stdio.h>
#include <lcjmp.h>
#include <stdlib.h>

jmp_buf env;
void dummy();

main()
{
   int errcode;
      /* Allow restart via longjmp. */
   onjmp(env, errcode,cleanup);
   dummy();
   puts("No error occurred in dummy routine.");
   return;
   cleanup:
   printf("Beginning cleanup for error number %d\n", errcode);
}

void dummy()
{
   puts("Entering dummy routine.");
   longjmp(env, 3);
   puts("Never reached.");
}

RELATED FUNCTIONS

longjmp , setjmp

SEE ALSO

• Program Control Functions

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Copyright © 2001 by SAS Institute Inc., Cary, NC, USA. All rights reserved.