Good code

// Needed header files
#include <iostream>  // Console I/O
#include <string>    // String support
#include <windows.h> // Sleep statement

using namespace std; // So I don't have to type std::

class App // Application functions
{
    public:
        float getValue() // Get a number from user
        {
            float num;
            cout << "Enter a number..." << endl;
            cin >> num;
            cout << "\n";
            return num;
        }

        string getOp()  // Get the operation from user
        {
            string op;
            cout << "What operation do you want to perform?" << endl;
            cin >> op;
            cout << "\n";
            return op;
        }
};

class Math // Math operations
{
    public:
        float Add(float a, float b)
        {
            return a + b;
        }

        float Subtract(float a, float b)
        {
            return a - b;
        }

        float Multiply(float a, float b)
        {
            return a * b;
        }

        float Divide(float a, float b)
        {
            return a / b;
        }
};

int main()
{
    try  // For errors
    {
        App App;   // App class object
        Math Math; // Math class object

        cout << "Welcome to cCalc.\n" << "by: Brendan Gowen\n" << "http://www.github.com/thatoneguy107\n\n";

        // Numbers for calculation
        float x = App.getValue();
        float y = App.getValue();

        string operation = App.getOp();

        if (operation == "add")
        {
            cout << "The answer is: " << Math.Add(x, y);
        }
            cout << "The answer is: " << Math.Add(x, y);
        }

        if (operation == "subtract")
        {
            cout << "The answer is: " << Math.Subtract(x, y);
        }

        if (operation == "multiply")
        {
            cout << "The answer is: " << Math.Multiply(x, y);
        }

        if (operation == "divide")
        {
            cout << "The answer is: " << Math.Divide(x, y);
        }

        Sleep(3000); // Allow user to see output

        return 0;
    }

    catch(...) // Unexpected exception handling
    {
        cout << "Unexpected error." << endl;
    }
}