Try catch statements in C

Question

I was thinking today about the try/catch blocks existent in another languages. Googled for a while this but with no result. From what I know, there is not such a thing as tr

Answer 1

Warning: the following is not very nice but it does the job.

#include 
#include 

typedef struct {
    unsigned int  id;
    char         *name;
    char         *msg;
} error;

#define _printerr(e, s, ...) fprintf(stderr, "\033[1m\033[37m" "%s:%d: " "\033[1m\033[31m" e ":" "\033[1m\033[37m" " ‘%s_error’ " "\033[0m" s "\n", __FILE__, __LINE__, (*__err)->name, ##__VA_ARGS__)
#define printerr(s, ...) _printerr("error", s, ##__VA_ARGS__)
#define printuncaughterr() _printerr("uncaught error", "%s", (*__err)->msg)

#define _errordef(n, _id) \
error* new_##n##_error_msg(char* msg) { \
    error* self = malloc(sizeof(error)); \
    self->id = _id; \
    self->name = #n; \
    self->msg = msg; \
    return self; \
} \
error* new_##n##_error() { return new_##n##_error_msg(""); }

#define errordef(n) _errordef(n, __COUNTER__ +1)

#define try(try_block, err, err_name, catch_block) { \
    error * err_name = NULL; \
    error ** __err = & err_name; \
    void __try_fn() try_block \
    __try_fn(); \
    void __catch_fn() { \
        if (err_name == NULL) return; \
        unsigned int __##err_name##_id = new_##err##_error()->id; \
        if (__##err_name##_id != 0 && __##err_name##_id != err_name->id) \
            printuncaughterr(); \
        else if (__##err_name##_id != 0 || __##err_name##_id != err_name->id) \
            catch_block \
    } \
    __catch_fn(); \
}

#define throw(e) { *__err = e; return; }

_errordef(any, 0)

Usage:

errordef(my_err1)
errordef(my_err2)

try ({
    printf("Helloo\n");
    throw(new_my_err1_error_msg("hiiiii!"));
    printf("This will not be printed!\n");
}, /*catch*/ any, e, {
    printf("My lovely error: %s %s\n", e->name, e->msg);
})

printf("\n");

try ({
    printf("Helloo\n");
    throw(new_my_err2_error_msg("my msg!"));
    printf("This will not be printed!\n");
}, /*catch*/ my_err2, e, {
    printerr("%s", e->msg);
})

printf("\n");

try ({
    printf("Helloo\n");
    throw(new_my_err1_error());
    printf("This will not be printed!\n");
}, /*catch*/ my_err2, e, {
    printf("Catch %s if you can!\n", e->name);
})

Output:

Helloo
My lovely error: my_err1 hiiiii!

Helloo
/home/naheel/Desktop/aa.c:28: error: ‘my_err2_error’ my msg!

Helloo
/home/naheel/Desktop/aa.c:38: uncaught error: ‘my_err1_error’ 

Keep on mind that this is using nested functions and __COUNTER__. You'll be on the safe side if you're using gcc.