C + + Class 32 operator overloading-assignment

#include <iostream>
using namespacestd;classfi{ Public: Fi () {cout<<"Fi::fi ()"<<Endl;}};classfee{ Public: Fee (int) {cout<<"fee::fee (int)"<<Endl;} Fee (Constfi&) {cout<<"Fee::fee (fi&)"<<Endl;} fee&operator=(Constfee& RHS) {cout<<"fee::operator="<<Endl;
if (THIS!=&RHS) {//perform Assignment}
return *this; }};intMain () {Fee Fee=1;//Fee (int)fi fi; Fee Fum=fi;//Fee (Fi);Fum=fi;//first, a fee object is constructed with fi, and then the assignment operation is called.}

Operation Result:

Fee::fee (int) Fi::fi () Fee::fee (fi&) Fee::fee (fi&) Fee::operator =

1, Copying vs. initialization

MyType b;

MyType a = b; Copy Construction

A = b; Assign value

2, Automatic operator= creation

The compiler would automatically create a type::operator= (type) if you don ' t make one.

memberwise Assignment

3, Operator overloading-assignment: must be a member function, assign yourself a value and return yourself

t& T::operator= (const t& RHS) {    //check for self assignment    if(this!=&rhs) {        //perform assignment     }     return *this;}

The following example shows why you need to judge THIS!=&RHS

class a{    Char *p;    Aoperator= (const a& that ) {        delete  p;          P=new [Strlen (THAT.P) +1// If you assign yourself, THAT.P has been deleted;         strcpy (P,THAT.P);         return *this;    }}

4. For classes with dynamically allocated memory declare an assignment operator (and a copy construct or)

--The above content is from "object-oriented Programming C + + course (Onke)"

C + + Class 32 operator overloading-assignment