C setjmp/longjmp based exception system

c_exceptions.c

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

union exception_data
{
	const char *string;
	double d;
	int i;
};

enum exception_type
{
	STRING,
	DOUBLE,
	INT
};

struct exception_status
{
	union exception_data d;
	enum exception_type t;
	jmp_buf buf;
};

void generic_throw( struct exception_status *ex )
{
	longjmp( ex->buf, 1 );
}

void throw_string( struct exception_status *ex, const char *str )
{
	ex->d.string = str;
	ex->t = STRING;
	generic_throw( ex );
}

void throw_int( struct exception_status *ex, int i )
{
	ex->d.i = i;
	ex->t = INT;
	generic_throw( ex );
}

void throw_double( struct exception_status *ex, double d )
{
	ex->d.d = d;
	ex->t = DOUBLE;
	generic_throw( ex );
}

void generic_catch( const struct exception_status *ex )
{
	switch ( ex->t )
	{
		case STRING:
			fprintf( stderr, "caught string: %s\n", ex->d.string );
			break;
			
		case INT:
			fprintf( stderr, "caught int: %d\n", ex->d.i );
			break;
			
		case DOUBLE:
			fprintf( stderr, "caught double: %f\n", ex->d.d );
			break;
	
		default:
			fprintf( stderr, "uncaught exception\n" );
			break;
	}
}

#define generic_try(ex) (!setjmp((ex)->buf))

struct exception_status EX;

int main( )
{
	if ( generic_try( &EX ) )
	{
		//throw_string( &EX, "hahah" );
		throw_int( &EX, 78 );
	}
	else
	{
		generic_catch( &EX );
	}

	return 0;
}