Calc through "cls"

    #include <iostream>
#include <conio.h>

using std::cout;
using std::cin;
using std::endl;

void main()
{
    double src = (cin >> src, src);
    char sign = 0;

    sign = (cin >> sign, sign);
    do
    {
        int temp = (cin >> temp, temp);

        system("cls");

        switch (sign)
        {
            cin >> temp;
        case '+':
            cout << (src += temp) << " ";
            break;
        case '-':
            cout << (src -= temp) << " ";
            break;
        case '*':
            cout << (src *= temp) << " ";
            break;
        case '/':
            cout << (src /= temp) << " ";
            break;
        }

        sign = getch();
        if(sign != 27) cout << sign;

    } while (sign != 27);
}