prefix and postfix operator overloading in c 2b 2b

1struct X
2{
3    // prefix increment
4    X& operator++()
5    {
6        // actual increment takes place here
7        return *this; // return new value by reference
8    }
9 
10    // postfix increment
11    X operator++(int)
12    {
13        X old = *this; // copy old value
14        operator++();  // prefix increment
15        return old;    // return old value
16    }
17 
18    // prefix decrement
19    X& operator--()
20    {
21        // actual decrement takes place here
22        return *this; // return new value by reference
23    }
24 
25    // postfix decrement
26    X operator--(int)
27    {
28        X old = *this; // copy old value
29        operator--();  // prefix decrement
30        return old;    // return old value
31    }
32};

1class Point
2{
3public:
4	Point& operator++() { ... }		// prefix
5	Point operator++(int) { ... }	// postfix
6  	friend Point& operator++(Point &p);			// friend prefix
7  	friend Point operator++(Point &p, int);		// friend postfix
8  	// in Microsoft Docs written "friend Point& operator++(Point &p, int);"
9};
10