Casting away const.

cast-away-const.cpp

#include <iostream>

using namespace std;

class Class
{
public:
    char c = 'c';
};

void manipulate (Class & c)
{
    ++c.c;
}

void manipulate2 (const Class & c)
{
    Class & c2 = const_cast<Class &>(c);
    ++c2.c;
    cout << "Original address: " << int(&c.c) << endl << "Copied address  : " << int(&c2.c) << endl;
}

void display (const Class & c)
{
    cout << "The char is: " << c.c << endl;
}

int main()
{
    const Class c;

    display (c);
    //manipulate(c); // Not allowed because c is const!
    manipulate2 (c); // Allowed even though c is const.
    display (c);

    return 0;
}

The char is: c
Original address: 2686783
Copied address  : 2686783
The char is: d