Exception handling in C

exhnd.c

/* Author: http://twitter.com/jaz303  */

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

#define THROW(str) \
	if (exception_count < 0) { \
		fprintf(stderr, "unhandled exception '%s' at line %d in %s\n", str, __LINE__, __FILE__); \
		exit(1); \
	} \
	exception_thrown = str; \
	longjmp(exception_stack[exception_count--], 0)
	
#define THROW_AGAIN THROW(exception_thrown)

#define TRY \
	{ \
		int exception_status; \
		if ((exception_status = setjmp(exception_stack[++exception_count])) == 0)
		
#define CATCH(str) else if (exception_status > 0 && strcmp(str, exception_thrown) == 0)

#define ENDTRY \
		else { \
			THROW_AGAIN; \
		} \
	} 0

jmp_buf	exception_stack[50];
int		exception_count		= -1;
char* 	exception_thrown	= NULL;

char*	exception_to_throw;

int bar() {
	THROW(exception_to_throw);
}

int foo() {
	printf("IN foo()\n");
	TRY {
		bar();
	} CATCH("foo") {
		printf("caught a foo in foo()\n");
		THROW_AGAIN;
	} CATCH("bar") {
		printf("caught a bar in foo()\n");
	} ENDTRY;
	printf("OUT foo()\n");
}

int main(int argc, char *argv[]) {
	if (argc != 2) {
		fprintf(stderr, "Usage: except exception_to_throw\n");
		exit(1);
	}
	exception_to_throw = argv[1];
	
	TRY {
		foo();
	} CATCH("foo") {
		printf("caught a foo in main()\n");
	} ENDTRY;
	
	return 0;
}