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setjmp
Saves the current environment.
Syntax
#include <setjmp.h>
int setjmp (jmp_buf env);
Parameters
env An array of unsigned integers as defined by the type
jmp_buf.
Return Values
0 Successful completion of setjmp().
!=0 Returned as a result of a call to longjmp(). The value
returned is the value passed in the val parameter of
longjmp().
Description
The setjmp macro creates an entry point in your program that can be
reached with longjmp().
The setjmp macro saves the current environment of the calling process in
the env parameter. The parameter env is of type jmp_buf, defined in
<setjmp.h>. It is an array of unsigned integers and therefore the env
argument does not require an & operator.
A subsequent call to longjmp() requires that the env variable initialized
by setjmp() be passed as a parameter. This allows longjmp() to restore
the program environment saved by setjmp() and to continue program
execution just after the setjmp() statement.
Upon successful completion, the setjmp() macro returns a zero value. A
zero indicates that the return is from setjmp() itself and not a return
as a result of a call to longjmp().
If a nonzero value is returned, this indicates that the return is a
result of a call to longjmp(). After the call to longjmp() is completed,
the program executes as if the call to setjmp() (which stored information
into the env argument) had returned a second time. The result of the
second return from setjmp() is the return of the value of the nonzero val
argument supplied to longjmp().
See Also
longjmp(), ANSI C 4.6.1.1, POSIX.1 8.1