Restores stack environment and execution locale.
#include <setjmp.h>
void longjmp( jmp_buf env, int value );
| env | Variable in which environment is stored | |
| value | Value to be returned to setjmp call |
The longjmp function restores a stack environment and execution locale previously saved in env by setjmp. The setjmp and longjmp functions provide a way to execute a nonlocal goto; they are typically used to pass execution control to error handling or recovery code in a previously called routine without using the normal call and return conventions.
A call to setjmp causes the current stack environment to be saved in env. A subsequent call to longjmp restores the saved environment and returns control to the point immediately following the corresponding setjmp call. Execution resumes as if value had just been returned by the setjmp call. The values of all variables (except register variables) that are accessible to the routine receiving control contain the values they had when longjmp was called. The values of register variables are unpredictable.
The longjmp function must be called before the function that called setjmp returns. If longjmp is called after the function calling setjmp returns, unpredictable program behavior results.
The value returned by setjmp must be nonzero. If value is passed as 0, the value 1 is substituted in the actual return.
Observe the following four restrictions when using longjmp:
Do not assume that the values of the register variables will remain the same. The values of register variables in the routine calling setjmp may not be restored to the proper values after longjmp is executed. Do not use longjmp with the global register allocation (/Oe) option to the CL driver.
Do not use longjmp to transfer control from within one overlay to within another. The overlay manager keeps the overlay in memory after a call to longjmp.
Do not use longjmp to transfer control out of an interrupt-handling routine unless the interrupt is caused by a floating-point exception. In this case, a program may return from an interrupt handler via longjmp if it first reinitializes the floating-point math package by calling _fpreset.
Do not use longjmp or setjmp from a C++ program.
None.
Standards:ANSI, UNIX
16-Bit:DOS, QWIN, WIN, WIN DLL
32-Bit:DOS32X
See the example for _fpreset.