C++ Overload (Перегрузка)

[netcat-na-diary]

myObject < something
bool MyClass::operator<(OtherType something)

Person.h

#include <string>
using namespace std;
#ifndef _Person_H
#define _Person_H
class Person 
{
private:
	string firstname;
	string lastname;
	int arbitrarynumber;

public:
	Person(string first, 
		string last,
		int arbitrary);
	
	~Person();

	string GetName();
	int GetNumber() {return arbitrarynumber;}
	void SetNember(int number) {arbitrarynumber = number;}
	bool operator<(Person& p);
	bool operator<(int i);
};
bool operator<(int i, Person& p); //free function
#endif

Person.cpp

#include "stdafx.h"

#include "Person.h"
#include <iostream>

Person::Person(string first, string last, int arbitrary) : firstname(first), lastname(last), arbitrarynumber (arbitrary)
{
	cout << "constructing " << GetName() << endl;
}

Person::~Person()
{
	cout << "destructing " << GetName() << endl ;
}

string Person::GetName()
{
	return firstname + " " +  lastname;
}

bool Person::operator<(Person& p)
{
	return arbitrarynumber < p.arbitrarynumber;
}

bool Person::operator<(int i)
{
	return arbitrarynumber < i;
}

bool operator<(int i, Person& p)
{
	return i < p.GetNumber();
}

Использование в программе
ClassesAndObjects.cpp

#include "stdafx.h"
#include "Person.h"
#include "status.h"
#include <iostream>
 
int _tmain(int argc, _TCHAR* argv[])
{
	Person p1 ("Kate", "Gregory", 20);
	Person p2 ("Tanya", "Fomina", 87);
	
	cout << "p1 is ";
	if (!(p1 < p2))
		cout << "not ";
	cout << "less than p2" << endl;

	cout << "p1 is ";
	if (!(p1 < 65))
		cout << "not ";
	cout << "less than 65" << endl;

	cout << "65 is ";
	if (!(65 < p1))
		cout << "not ";
	cout << "less than p1" << endl;

	return 0;
}

friend (C++) разрешает функции или классу доступ к закрытым и защищенным членам класса.

#define _Person_H
class Person 
{
private:
	string firstname;
	string lastname;
	int arbitrarynumber;

public:
	Person(string first, 
		string last,
		int arbitrary);
	
	~Person();

	string GetName();
	int GetNumber() {return arbitrarynumber;}
	void SetNember(int number) {arbitrarynumber = number;}
	bool operator<(Person& p);
	bool operator<(int i);
	friend bool operator<(int i, Person& p);
};
#endif

В таком случае можно переписать файл кода Person.cpp таким образом

#include "stdafx.h"

#include "Person.h"
#include <iostream>

Person::Person(string first, string last, int arbitrary) : firstname(first), lastname(last), arbitrarynumber (arbitrary)
{
	cout << "constructing " << GetName() << endl;
}

Person::~Person()
{
	cout << "destructing " << GetName() << endl ;
}

string Person::GetName()
{
	return firstname + " " +  lastname;
}

bool Person::operator<(Person& p)
{
	return arbitrarynumber < p.arbitrarynumber;
}

bool Person::operator<(int i)
{
	return arbitrarynumber < i;
}

bool operator<(int i, Person& p)
{
	return i < p.arbitrarynumber;
}