C + + Friend

Friend is a friend and friend of the class.

Friend function: A friend function of a class can access the private members of the class

We can use the member functions of one class (including constructs, destructors) as friend functions of another class. As follows

classCcar;//declare the Ccar class in advance so that the following Cdriver class uses theclassCdriver { Public:    voidModifycar (Ccar *pcar);//Modified Car};classCcar {Private:    intPrice ; FriendintMostexpensivecar (Ccar cars[],intTotal);//declare as FriendFriendvoidCdriver::modifycar (Ccar *pcar);//Declare friend};voidCdriver::modifycar (CCAR *Pcar) {Pcar->price + = +;}intMostexpensivecar (Ccar cars[],intTotal ) {    intTmpmax =-1;  for(inti =0; I < total; ++i) {if(Cars[i].price >Tmpmax) {Tmpmax=Cars[i].price; }    }    returnTmpmax;}intMain () {return 0;}

Friend class

A is a friend of B, then A's member function can access the private member of B.

Note: Relationships between friend classes cannot be passed and cannot be inherited.

The following code

classCcar {Private:    intPrice ; FriendclassCdriver;//declare cdriver as friend class};classCdriver { Public: Ccar MyCar; voidModifycar () {//Modified CarMycar.price + = +; }};intMain () {return 0;}

C + + Friend