Exception Handling C vs C++

Exception.cpp

/*
	What: 	Exception using throw and jmp/longjmp
	Author: Sid
	Note:	Test run with 3 cases
	1: x(10), y(2) : Returns 2
	2: x(10), y(0) : Catch exception DIVIDE_EXCP, prints error and quit
	3: x(10), y(-2) : Catch exception NEG_EXCP, does nothing
*/

#include <iostream>
#include <csetjmp>
//Catch this exception
#define DIVIDE_EXCP 1
//Don't catch this
#define NEG_EXCP 2

//Using throw
double divide(const double &x, const double &y){
	if(y == 0){
		throw DIVIDE_EXCP;
	}else if(y < 0){
		throw NEG_EXCP;
	}
	return x/y;
}

void newway(const double &x, const double &y){
	try{
		std::cout << "NEW: " << divide(x, y) << std::endl;
	}catch(int catch_excp){
		if(catch_excp == DIVIDE_EXCP){
			std::cout << "NEW: Divide by zero not allowed" << std::endl;
		}else{
			std::cout << "NEW: Uncaught exception" << std::endl;
		}
	}
}

//Using the setjmp/longjmp way
double divide(const double &x, const double &y, jmp_buf env){
	if(y == 0){
		longjmp(env, DIVIDE_EXCP);
	}else if(y < 0){
		longjmp(env, NEG_EXCP);
	}
	return x/y;
}

void oldway(const double &x, const double &y){
	jmp_buf env;
	int catch_excp = setjmp(env);
	if(catch_excp == 0){
		std::cout << "OLD: " << divide(x, y, env) << std::endl;
	}else if(catch_excp == DIVIDE_EXCP){
		std::cout << "OLD: Divide by zero not allowed" << std::endl;
		return;
	}else{
		std::cout << "OLD: Uncaught exception" << std::endl;
	}
}

int main(int argc, char **argv){
	if(argc != 3){
		std::cout << "Usage: " << argv[0] << " x y" << std::endl;
		return 0;
	}
	double x = atof(argv[1]);
	double y = atof(argv[2]);
	oldway(x, y);
	newway(x, y);
	return 0;
}