Primitive try/catch Exception Handling in C

gistfile1.c

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

struct Exception {
    jmp_buf jb;
    int code;
};

/* Definitely not thread-safe... But we don't care :-) */
struct Exception *cur_ex_ptr = NULL;

#define try(in_ex) {\
    (in_ex).code = 0;\
    cur_ex_ptr = &(in_ex);\
} if (!setjmp((in_ex).jb))

#define catch(in_arg) else if (in_arg)

#define raise(in_code) {\
    if (cur_ex_ptr != NULL) {\
        cur_ex_ptr->code = in_code;\
        jmp_buf *tmp = &cur_ex_ptr->jb;\
        cur_ex_ptr = NULL;\
        longjmp((*tmp), in_code);\
    }\
}

void nested_func()
{
    // Oops, this function raises an exception
    raise(1);
}

int main(int argc, char **argv)
{
    struct Exception ex;
    
    try (ex) {
        printf("Try Block 1\n");
    } catch (ex.code > 0) {
        printf("This is never seen\n");
    }
    
    try (ex) {
        printf("Try Block 2\n");
        nested_func();
    } catch (ex.code > 0) {
        printf("Exception Raised: %d\n", ex.code);
    }

    return 0;
}

To see the macros expanded, run (clang or gcc):

clang -E gistfile1.c