6.12.2 longjmp Function

A function that restores the environment saved by setjmp.

Include

<setjmp.h>

Prototype

void longjmp(jmp_buf env, int val);

Arguments

env

variable where environment is stored

val

value to be returned to setjmp call

Remarks

The value parameter, val, should be non-zero. If longjmp is invoked from a nested signal handler (that is, invoked as a result of a signal raised during the handling of another signal), the behavior is undefined.

Example

See the notes at the beginning of this chapter or section for information on using printf() or scanf() (and other functions reading and writing the stdin or stdout streams) in the example code.

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

jmp_buf jb;

void inner (void)
{
    longjmp(jb, 5);
}
int main (void)
{
  int i;
  if((i = setjmp(jb))) {
    printf("setjmp returned %d\n" i);
    exit(0);
  }
  printf("setjmp returned 0 - good\n");
  printf("calling inner...\n");
  inner();
  printf("inner returned - bad!\n");
}

Example Output

setjmp returned 0 - good
calling inner...
setjmp returned 5