C++ increment operator

Question

How to differentiate between overloading the 2 versions of operator ++ ?

const T& operator ++(const T& rhs)

which one?

i++;
++i;

Answer 1

For the non-member versions, a function with one parameter is prefix while a function with two parameters and the second being int is postfix:

struct X {};
X& operator++(X&);      // prefix
X  operator++(X&, int); // postfix

For the member-versions, the zero-parameter version is prefix and the one-parameter version taking int is postfix:

struct X {
    X& operator++();    // prefix
    X  operator++(int); // postfix
};

The int parameter to calls of the postfix operators will have value zero.