#include "stdafx.h"
using namespace std;
bool err = false;
double x, y;
char op;

double calc (double x, char op, double y);
void vvod_vivod();

int main()
{
	vvod_vivod();

}


void vvod_vivod()
{
char rep;
do
	{
		cout << "press math operation: ";
		cin >> x >> op >> y;
		if ( cin.good() == false )
			err = true;
		
			if (err == 0)
				cout <<  "Otvet: " <<  calc(x,op,y) << endl;
			else 
				cout << "ERROR!! \n";
		cout << "Repeat? [y/n] ";
		cin >> rep;
	}
while (rep == 'Y' || rep == 'y');
}


double calc (double x, char op, double y)
{
	switch (op)
	{
		case '+': 
			return x+y; break; 
		case '-': 
			return x-y; break;
		case '*': 
			return x*y; break;
		case '/': 
			if (y == 0){err = true; break;}
			else { return x/y; break;} 
	}	
}