Singleton

// singletone.cpp : Defines the entry point for the console application.
//
// A singleton is a class which can only be instantiated once. This
// can be useful when you want an object to have shared single state
// across your application. One way of thinking of singletons is like
// global variables.

#include "stdafx.h"
#include <iostream>

class Singleton {
public:
    static Singleton& getInstance() {
        static Singleton instance; // Guaranteed to be destroyed
                                   // Instantiated on first use
        return instance;
    }

    int getCounter() {
        return counter;
    }
private:
    Singleton() : counter(0) { counter++; } // Constructor? (the {} brackets) are needed here
    int counter;
public:
    // C++ 11
    // ========
    // We can use a better technique for deleting methods
    // we don't want
    Singleton(Singleton const&) = delete;
    void operator= (Singleton const&) = delete;
};


int main()
{
    // Should print
    // 1
    // 1
    // 1
    // 1
    std::cout << Singleton::getInstance().getCounter() << std::endl;
    std::cout << Singleton::getInstance().getCounter() << std::endl;
    std::cout << Singleton::getInstance().getCounter() << std::endl;
    std::cout << Singleton::getInstance().getCounter() << std::endl;

    system("PAUSE");
    return 0;
}