Overloaded operator "<" and friend property in C + +

Overloaded operators in a class do not need to be member functions, or they can be declared as friend functions.

classperson{ Public://as a member function of a class, overloaded operator arguments require only the right action value to    BOOL operator< (Constperson&Arg);Private:   intA;};//Class name qualification is required for implementation BOOLPerson::operator< (Constperson&Arg) {    if( ( This->a) <arg.a)return true; Else        return false;} Person A1,A2;BOOLBRet = A1 < A2; That's right

Class Person

{

Public:

as a member function of a class, overloaded operator arguments require only the right action value to

friend booloperator< (Const person&Arg1,Const person& arg 2);

Private:

IntA

};

//Class name qualification is not required for implementation

bool operator< (const person& arg1, const person& arg2)
{
if ( arg1.a < arg2.a)
return true;
Else
return false;

}

Person A1,A2;

BOOL BRet = A1 < A2; That's right

In this example 1, the operator overloads the function as a member function of the class, and you can invoke the internal private protected member when using the object of that class.

In Example 2, the operator overload function, although not a member function of a class, is declared as a friend function of the class, and can also invoke a private protected member inside the class.

However, if you declare an overloaded function as a protection or private function, the overloaded function cannot be called when you use an object of that class, that is, if you write the overloaded function as a member function or a friend function, and it is a public property, there is no difference in using the operator, but if it is protected or private, Then outside you can't use the operator:

classperson{Protect: //as a member function of a class, overloaded operator arguments require only the right action value to    BOOL operator< (Constperson&Arg);Private:   intA;};//Class name qualification is required for implementation BOOLPerson::operator< (Constperson&Arg) {    if( ( This->a) <arg.a)return true; Else        return false;} Person A1,A2;BOOLBRet = A1 < A2; Error

classperson{Protect: //as a member function of a class, overloaded operator arguments require only the right action value tofriendBOOL operator< (Constperson& Arg1,Constperson&arg2);Private:   intA;};//class name qualification is not required for implementation BOOL operator< (Constperson& Arg1,Constperson&arg2) {    if(Arg1.a <arg2.a)return true; Else        return false;} Person A1,A2;BOOLBRet = A1 < A2; Error

Overloaded operator "<" and friend property in C + +