setjmp.h

• longjmp
• setjmp

longjmp

Header

setjmp.h

Prototype

void longjmp(jmp_buf env, int value);

Description

The longjmp function allows a goto between functions. It is good for dealing with errors or interrupts encountered in low-level subroutines of a program. longjmp restores the environment previously saved by setjmp in a jmp_buf pointed to by envp. The return value is that of setjmp. The environment must have been previously saved using setjmp by a function that is currently active, and which is the same function or a parent of the function containing the call to longjmp. After completion of longjmp, program execution continues just as if the corresponding call to setjmp had just returned with value. The value will never be 0. If value is passed as 0, the value 1 will be returned.

Return Value

None

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

setjmp

Example

/* 	Example for longjmp 
	Also demonstrates setjmp 
*/ 
#include <setjmp.h> 
#include <stdio.h>
#include <stdlib.h>

jmp_buf environment; 
int error_val = -1; 

void docall(void) 
{   
   longjmp(environment, error_val); 
} 
void main() 
{   
   int error_code; 

   error_code = setjmp(environment); 
   if (error_code != 0) 
   {   
      printf ("Longjmp called\n"); 
      exit (EXIT_FAILURE); 
   } 
   printf("Setjmp called\n"); 
   docall(); 
} 

Output

Setjmp called
Longjmp called 

setjmp

Header

setjmp.h

Prototype

int setjmp(jmp_buf env);

Description

Coupled with longjmp, setjmp allows a "goto" between functions. Jumps are good for dealing with errors or interrupts encountered in low-level subroutines of a program.

Synonym

Function: _setjmp

Return Value

setjmp returns a 0 when it is called to save the environment for a subsequent longjmp call; its value is that of the longjmp argument. If the longjmp argument is 0, it is changed to 1.

Compatibility

DOS Windows 3.x Phar Lap DOSX Win32

See Also

longjmp