NAME¶

std::jmp_buf - std::jmp_buf

Synopsis¶

Defined in header <csetjmp>
typedef /* unspecified */ jmp_buf;

The std::jmp_buf type is an array type suitable for storing information to restore a
calling environment. The stored information is sufficient to restore execution at
the correct block of the program and invocation of that block. The state of
floating-point status flags, or open files, or any other data is not stored in an
object of type jmp_buf.

Example¶

// Run this code

#include <iostream>
#include <csetjmp>

std::jmp_buf my_jump_buffer;

[[noreturn]] void foo(int count)
{
std::cout << "foo(" << count << ") called\n";
std::longjmp(my_jump_buffer, count+1); // setjmp() will return count+1
}

int main()
{
volatile int count = 0; // modified locals in setjmp scope must be volatile
if (setjmp(my_jump_buffer) != 5) { // equality against constant expression in an if
count = count + 1; // ++count, count += 1, etc on 'volatile'-qualified
// left operand are deprecated since C++20 (P1152)
foo(count); // This will cause setjmp() to exit
}
}

Output:¶

foo(1) called
foo(2) called
foo(3) called
foo(4) called

See also¶

setjmp saves the context
(function macro)
longjmp jumps to specified location
(function)