How to throw an exception in C?

Question

I typed this into google but only found howtos in C++,

how to do it in C?

Answer 1

There are no exceptions in C. Exceptions defined in C++ and other languages though.

Exception handling in C++ is specified in the C++ standard "S.15 Exception handling", there is no equivalent section in the C standard.

Answer 2

C doesn't have exceptions.

There are various hacky implementations that try to do it (one example at: http://adomas.org/excc/).

Answer 3

Plain old C doesn't actually support exceptions natively.

You can use alternative error handling strategies, such as:

• returning an error code
• returning FALSE and using a last_error variable or function.

See http://en.wikibooks.org/wiki/C_Programming/Error_handling.

Answer 4

C doesn't support exceptions. You can try compiling your C code as C++ with Visual Studio or G++ and see if it'll compile as-is. Most C applications will compile as C++ without major changes, and you can then use the try... catch syntax.

Answer 5

On Win with MSVC there's _try ... __except ... but it's really horrible and you don't want to use it if you can possibly avoid it. Better to say that there are no exceptions.

Answer 6

In C you should use setjmp/longjmp defined in setjmp.h. Example from Wikipedia

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

static jmp_buf buf;

void second(void) {
    printf("second\n");         // prints
    longjmp(buf,1);             // jumps back to where setjmp 
                                //   was called - making setjmp now return 1
}

void first(void) {
    second();
    printf("first\n");          // does not print
}

int main() {   
    if ( ! setjmp(buf) ) {
        first();                // when executed, setjmp returns 0
    } else {                    // when longjmp jumps back, setjmp returns 1
        printf("main");         // prints
    }

    return 0;
}

Note: I would actually advise you not to use them as they work awful with C++ (destructors of local objects wouldn't get called) and it is really hard to understand what is going on. Return some kind of error instead.