Purpose of Dummy Parameter in Postfix Operator Overload? c++

Question

When overloading the postfix operator, I can do something simple like

Class Foo
{
private: 
   int someBS;
public:
   //declaration of  pre &postfix++
           


        

Answer 1

Citing C++reference here:

Prefix versions of the built-in operators return references and postfix versions return values, and typical user-defined overloads follow the pattern so that the user-defined operators can be used in the same manner as the built-ins.

Explaining this logically:

int a = 3;
int b = 0;

int c = a + ++b;
int d = a++ + b;

In the third line, ++b gives you a reference to the updated value; in the fourth line, that's not possible: a has to be increased, so a value-copy is made, and added to b. That dictates different semantics for the operators.

In fact, just to avoid having another operator name:

The int parameter is a dummy parameter used to differentiate between prefix and postfix versions of the operators. When the user-defined postfix operator is called, the value passed in that parameter is always zero, although it may be changed by calling the operator using function call notation (e.g., a.operator++(2) or operator++(a, 2)).