std::longjmp

 

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setjmp
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Defined in header <csetjmp>
void longjmp( std::jmp_buf env, int status );

Loads the execution context env saved by a previous call to setjmp. This function does not return. Control is transferred to the call site of the macro setjmp that set up env. That setjmp then returns the value, passed as the status.

If the function that called setjmp has exited, the behavior is undefined (in other words, only long jumps up the call stack are allowed)

No destructors for automatic objects are called. If replacing of std::longjmp with throw and setjmp with catch would execute a non-trivial destructor for any automatic object, the behavior of such std::longjmp is undefined.

Parameters

env	-	variable referring to the execution state of the program saved by std::setjmp
status	-	the value to return from setjmp. If it is equal to ​0​, 1 is used instead

Return value

(none)

Example

run this code

#include <iostream>
#include <csetjmp>
 
std::jmp_buf jump_buffer;
 
[[noreturn]] void a(int count) 
{
    std::cout << "a(" << count << ") called\n";
    std::longjmp(jump_buffer, count+1);  // setjump() will return count+1
}
 
int main()
{
    int count = setjmp(jump_buffer);
    if (count != 9) {
        a(count);  // This will cause setjmp() to exit
    }
}

Output:

a(0) called
a(1) called
a(2) called
a(3) called
a(4) called
a(5) called
a(6) called
a(7) called
a(8) called

See also

setjmp	saves the context (function macro)