C++ - Mutable

#include <iostream>
using namespace std;

class Foo
{
public:
	Foo()
	{
		Number = 0;
	}

	void bar() const
	{
		Number = 2; // mutable Variablen dürfen in konstanten Methoden verändert werden
	}

private:
	mutable int Number;
};

int main()
{
	Foo x;
	x.bar();
}