C longjmp function causes program to jump to a preset point set setjmp()

Syntax

C longjmp function has the following syntax.

Header

C longjmp function is from file setjmp.h.

Description

The longjmp() function causes program execution to resume at the point of the last call to setjmp(). longjmp() and setjmp() provide a means of jumping between functions.

The common use of longjmp() is to return from a deeply nested set of routines in case of error.

Example

Jump to a preset point set by setjmp() by using C longjmp function.

#include <setjmp.h>
#include <stdio.h>
//from   w w w  .  ja  v  a  2  s  . com
jmp_buf ebuf;
void f2(void);

int main(void)
{
  int i;

  printf("1 ");
  i = setjmp(ebuf);
  if(i == 0) {
    f2();
    printf("This will not be printed.");
  }
  printf("%d", i);

  return 0;
}

void f2(void)
{
  printf("2 ");
  longjmp(ebuf, 3);
}

The code above generates the following result.