C + + operator overloading three (chained programming)

//chained programming of operator overloading#include <iostream>using namespacestd;//the friend function overloading operator only applies to scenarios where the left operand is a system variable//Because members cannot add class member functions to system variables, only by global functionsthe essence of the chain programming is that the function returns the worth left-hand value
classpoint{ Public:    //Note in the friend function, the return value is different, the friend function will be different, and the function overload has a differenceFriend Ostream &operator<< (Ostream & out, point&pin); Point (intXinty) {         This->x =x;  This->y =y; } Point&p) {         This->x =p.x;  This->y =p.y; cout<<"the copy constructor was executed 1"<<Endl; }    ~Point () {cout<<"destructors have been executed for 2"<<Endl; }    voidPRINTFA () {cout<<"x="<< This->x <<Endl; cout<<"y="<< This->y <<Endl; }    Private:    intx; inty;};//first version (non-chained programming)/*void operator<< (ostream &out, point& pin) {out << "x=" << pin.x << Endl; Out << "y=" << pin.y << Endl;}*///second version (chained programming)Ostream &operator<< (Ostream & out, point&pin) {     out<<"x="<< pin.x <<Endl;  out<<"y="<< PIN.Y <<Endl; return  out;}voidProtecta () {point P1 (5,5); //Requirement: We need to print this class object, and the system cannot print the custom class, then we must overload the << operator//for a two-tuple operator, it is also critical to add a point and the position of two operands //For example: cout << P1, left operand is cout, right operand is P1, if write class member function then must cout.operator<< (p1)//Here we obviously cannot add operator overloads to the class that corresponds to the Cout object, only to make the UF meta-functioncout <<P1; //Step 1: First admit that operator overloading is a function that writes out the name of a functor//operator<< ()//Step 2: Write out the parameter list according to the operand//operator<< (COUT,P1)//Step 3: Return values based on business completion functions, and implement functions//the type of void operator<< (COUT,P1) cout is Ostream//The introduction of chained programming is now starting//for cout << p1<< "Asdfasdfas" <<endl; //cout << p1 << "Asdfasdfas" << Endl; Error C2296: "<<": illegal, left operand contains "void" type//This means that the void type has no overloaded operator <<, whereas the cout << P1 function should return the cout variable, then the output "Asdfasdfas" can be implemented//so the modification produces version twocout << P1 <<"Asdfasdfas"<<Endl;}voidMain () {protecta (); System ("Pause");}

C + + operator overloading three (chained programming)