setjmp
Saves the current state of the program.
Syntax
int setjmp(
jmp_buf env
);
Parameters
env
Variable in which environment is stored.
Return value
Returns 0 after saving the stack environment. If setjmp returns because of a longjmp call, it returns the value argument of longjmp, or if the value argument of longjmp is 0, setjmp returns 1. There's no error return.
Remarks
The setjmp function saves a stack environment, which you can subsequently restore, using longjmp. When used together, setjmp and longjmp provide a way to execute a non-local goto. They're 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 saves the current stack environment in env. A subsequent call to longjmp restores the saved environment and returns control to the point just after the corresponding setjmp call. All variables (except register variables) accessible to the routine receiving control contain the values they had when longjmp was called.
It isn't possible to use setjmp to jump from native to managed code.
Microsoft Specific
In Microsoft C++ code on Windows, longjmp uses the same stack-unwinding semantics as exception-handling code. It is safe to use in the same places that C++ exceptions can be raised. However, this usage isn't portable, and comes with some important caveats. For details, see longjmp.
END Microsoft Specific
Note
In portable C++ code, you can't assume setjmp and longjmp support C++ object semantics. Specifically, a setjmp/longjmp call pair has undefined behavior if replacing the setjmp and longjmp by catch
and throw would invoke any non-trivial destructors for any automatic objects. In C++ programs, we recommend you use the C++ exception-handling mechanism.
For more information, see Using setjmp and longjmp.
Requirements
| Routine | Required header |
|---|---|
setjmp |
<setjmp.h> |
For more compatibility information, see Compatibility.
Example
See the example for _fpreset.