//lerie taylor
//project 1 - c++
#include <iostream>
#include <cctype>
#include <limits>
#include <string>

using namespace std;
bool checkNum(string);

void main() {
	string nums;
	string dNum1, dNum2, dResult;
	char cCode;

	for(int iCount=0;iCount<=2;iCount++) {
		cout << "enter a number: ";
		cin >> nums;
		dNum1 = nums;

		//cout << checkNum(nums) << "\n";
		if(checkNum(nums)) {
			cout << "enter another number: ";
			cin >> nums;
			dNum2 = nums;

			cout << "enter a code, +, -, *, or / : ";
			cin >> cCode; //get the code

				switch(cCode) { //determine cCode
					case '+': dResult = dNum1+dNum2; break;
					case '-': dResult = dNum1-dNum2; break;
					case '*': dResult = dNum1*dNum2; break;
					case '/': dResult = dNum1/dNum2; break;
					default: cout << "error..." << endl;
				}

			cout << "result is " << dResult << endl;

		} else {
			cout << "error!";
		}
	}
}

bool checkNum(string num) {
	for(int i=0; i<(signed) num.length(); i++) {
		int j = num[i] - '0';
		if(j<0 || j>9) {
			return false;
		}
	}
	return true;
}