【C++第二阶段-重载-关系运算符函数调用】

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文章目录

关系运算符-重载-判断相等
函数调用运算符重载

关系运算符-重载-判断相等

场景：两个对象，若有年龄和性别的不同，是否可以直接通过比较运算符来比较，而不用单独地取出每个对象的成员属性单独比较？

代码实现：

#include<iostream>
#include<string>

using namespace std;
void test_0215_1();

class Person {
	friend void test_0215_1();

public:
	Person(int age , string name);
	~Person();
	bool operator==(Person& contrast);
	bool operator!=(Person& contrast);

private :
	int person_age;
	string person_name;
};

Person::Person(int age , string name) {
	cout << "有参构造函数调用" << "." << endl;
	person_age = age;
	person_name = name;
	cout << "age = " << age << "." << endl;
	cout << "name = " << name << "." << endl;
}

Person::~Person() {
	cout << "析构函数调用" << "." << endl;
}

bool Person::operator==(Person& contrast) {
	int this_variable = this->person_age;
	int person_variable = contrast.person_age;
	string this_name = this->person_name;
	string person_name = contrast.person_name;
	if (this->person_age == contrast.person_age && this->person_name == contrast.person_name) {
		return 1;
	}
	return 0;
}

bool Person::operator!=(Person& contrast) {
	int this_age = person_age;
	string this_name = person_name;
	if (person_age != contrast.person_age && person_name != contrast.person_name) {
		return 1;
	}
	return 0;
}


void test_0215_1() {
	Person per(15 , "Tom"), son(15 , "Tom");
	bool result = per == son;
	cout << "per == son ?==>" << (per == son ) << "." << endl;
	cout << "per != son ?==>" << (per != son) << "." << endl;
}


int main() {
	cout << "hello ! world ! " << endl;
	test_0215_1();
    system("pause");
    return 0;
}

运行结果：

可以看到，两者赋值都为"Tom15"，经过重载后。信息一致。

函数调用运算符重载

使用场景：传入不同的参数，实现不同的功能；匿名类使用。

代码展示：

#include<iostream>
#include<string>

using namespace std;
void test_0215_2();

class Print {
public:
	Print();
	void operator()(string con);
private:
	string print_context;
};

class Add {
public:
	int operator()(int num, int ber) {
		return num + ber;
	}
};

void Print::operator()(string con) {
	//第一个括号是重载的符号
	cout << con << "." << endl;
}

Print::Print() {
	//print_context = context;
}

void test_0215_2() {
	//Print print();//这样写会被当成函数的声明，返回值是Print，应该下面这样写
	Print print;
	string query = "hello ? world ? ";
	print(query);
	cout << "正常使用add功能" << "." << endl;
	int add = Add()(15, 20);
	cout <<"add = Add(15,20) ==> " << add << endl;
	cout << "匿名函数对象调用" << "." << endl;
	cout <<"Add()(20,20) ==> " << Add()(20, 20) << "." << endl;
}


int main() {
	cout << "hello ! world ! " << endl;
	test_0215_2();

	system("pause");
	return 0;

}