# <setjmp.h>

**[<setjmp.h>](https://en.cppreference.com/w/c/header/setjmp)** provides `setjmp` and `longjmp` for non-local jumps: save the current execution context and jump back to it from a deeply nested function, bypassing normal return chains. It's the C equivalent of exceptions but without cleanup machinery.

Use it sparingly—error codes or exceptions are usually clearer. Declare variables `volatile` to avoid register-caching pitfalls.

## Example

This example demonstrates error recovery using setjmp/longjmp to jump from a deep call stack.

```c
// compile: gcc -o setjmpexample setjmpexample.c
// run: ./setjmpexample
// description: non-local jump for error handling

#include <setjmp.h>
#include <stdio.h>

static jmp_buf err_env;

void level3() {
    printf("level3: error detected\n");
    longjmp(err_env, 1);
}

void level2() { level3(); }
void level1() { level2(); }

int main() {
    if (setjmp(err_env) == 0) {
        printf("calling level1...\n");
        level1();
        printf("never reached\n");
    } else {
        printf("caught error at top level\n");
    }
    return 0;
}
```