Calculator 1.2.0.0

#include <iostream>
#include <string>

using namespace std;

int main()
{

    string start = "";

    double num1;
    double num2;
    double result;
    int a;

    while (a != 5)
    {
        cout << "Copyright © 2012 Evan Malz, All rights reserved\n" << endl;
        cout << "Type 'Go' to start the calculator, 'Help' for i"
             << "nstructions, or 'Exit' to quit\n" << endl;
        cin >> start;
        // Asks for inputs 'go' or 'help'
        cout << "\n" << endl;

        if (start == "exit")
        {
            cout << "Press Enter to exit. \n";
            cin.ignore();
            cin.get();
            return 0;
            // Exits program if user imputs 'exit'
        }

        if (start == "help")
        {
            cout << "For steps 1 and 2, you will be asked to enter 2 nu"
                 << "mbers.\nFor step 3, you will choose an operation, "
                 << "for example,\nfor multiplication you would type '1"
                 << "'. You will return\nto Step 1 after receiving the "
                 << "answer to your calculation" << endl;
        }    // Text shown when 'help' is imput

        if (start == "go")
        {
            // Below is what will happen if the user imputs 'go'

            cout << "Step 1" << endl;
            cout << "Enter first integer: \n" << endl;
            // Asks for first number

            cin >> num1;
            // Defines 'num1' as the number imput above

            cout << "\n" << endl;

            cout << "Step 2" << endl;
            cout << "Enter second integer: \n" << endl;
            // Asks for second number

            cin >> num2;
            // Defines 'num2' as the number imput above

            cout << "\n" << endl;

            cout << "Step 3" << endl;
            cout << "Choose an operation below (Type only the number)"
                 << "\n\n1 = Multiply (x) ---- 5 = Exit calculator\n"
                 << "2 = Divide   (/)           \n3 = Add      (+)\n4 = "
                 << "Subtract (-)\n" << endl;
            // Asks for number of operation

            cin >> a;
            // Defines 'a' as the number imput above

            cout << "\n" << endl;
        }

        switch(a)
        {
        case 1:
            result = num1 * num2;
            cout << num1 << " x " << num2 << " = " << result << "\n"
                 << "";
            cout << "\n" << endl;
            cout << "When you're finished, type '5' at Step 3 to ex"
                 << "it\n" << endl;
            break;
            // This case is used if user types '1'. Selects multiplicat-
            // ion

        case 2:
            result = num1 / num2;
            cout << num1 << " / " << num2 << " = " << result << "\n"
                 << "";
            cout << "\n" << endl;
            cout << "When you're finished, type '5' at Step 3 to ex"
                 << "it\n" << endl;
            break;
            // This case is used if user types '2'. Selects division

        case 3:
            result = num1 + num2;
            cout << num1 << " + " << num2 << " = " << result << "\n"
                 << "";
            cout << "\n" << endl;
            cout << "When you're finished, type '5' at Step 3 to ex"
                 << "it\n" << endl;
            break;
            // This case is used if user types '3'. Selects addition

        case 4:
            result = num1 - num2;
            cout << num1 << " - " << num2 << " = " << result << "\n"
                 << "";
            cout << "\n" << endl;
            cout << "When you're finished, type '5' at Step 3 to ex"
                 << "it\n" << endl;
            break;
            // This case is used if user types '4'. Selects subtraction

        case 5:
            cout << "Thanks for using my calculator! Press Enter to"
                 << "exit" << endl;
            // This case is used if user types '5'. Exits program
            cout << "Press enter to exit. \n";
            cin.ignore();
            cin.get();
            return 0;
        }
    }
}