An example of using long jumps in C to jump interprocedurally

long_jump.c

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

// saves the stack context/environment for nonlocal gotos
jmp_buf env;

// foo immediately makes a long jump to the setjmp in main
void foo(void){
  longjmp(env,1);
}

// prints "hello cruel world!"
int main(int argc, char *argv[]){
   printf("hello");
   // setjmp returns 0 if returning directly and nonzero 
   // when returning from a longjmp or siglongjmp using
   // the saved stack context
   if (!setjmp(env)){
      foo();
      printf(" sane world!\n");
      return 0;  
   } else {
      printf(" cruel world!\n");
      return 1;
   }
}