◄Summary► ◄Example► ◄Up► ◄Contents► ◄Index► ◄Back► ─────Run-Time Library─────────────────────────────────────────────────────── The setjmp function saves a stack environment that can be subsequently restored using longjmp. Used together, setjmp and longjmp 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 calling or 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) 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 return value of setjmp, which is longjmp's <value> parameter, must be nonzero. If <value> is passed as 0, the value 1 is substituted in the actual return. Observe the following restrictions when using longjmp or setjmp: ■ Do not assume that the values of the register variables will remain the same. The values of the 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 error 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. ■ Neither setjmp nor longjmp is compatible with C++. Return Value The setjmp function returns 0 after saving the stack environment. If setjmp returns as a result of a longjmp call, it returns the value argument of longjmp. If the value argument of longjmp is 0, setjmp returns 1. There is no error return. -♦-