C++运算符重载
加号运算符重载
对于内置数据类型，编译器知道如何运算
但是对于自己封装的类，编译器无法进行运算
这时可以通过自己定义运算符重载进行运算
operator+
通过成员函数重载+号
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
//通过成员函数实现重载
Person operator+ (Person &p)
{
//创建一个临时变量
Person temp;
temp.m_a = this->m_a + p.m_a;
temp.m_b = this->m_b + p.m_b;
return temp;
}
};
void test01()
{
Person p1;
p1.m_a = 66;
p1.m_b = 44;
Person p2;
p2.m_a = 6;
p2.m_b = 4;
Person p3;
//通过函数原型调用
p3 = p1.operator+(p2);
//简便调用
//p3 = p1 + p2;
cout << "p3.m_a:" << p3.m_a << endl;
cout << "p3.m_b:" << p3.m_b << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
注意两种调用方式
通过函数原型调用
p3 = p1.operator+(p2);
简便调用
p3 = p1 + p2;
通过全局函数重载+号
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
};
//通过全局函数实现重载
Person operator+ (Person& p1, Person& p2)
{
//创建一个临时变量
Person temp;
temp.m_a = p1.m_a + p2.m_a;
temp.m_b = p1.m_b + p2.m_b;
return temp;
}
void test01()
{
Person p1;
p1.m_a = 66;
p1.m_b = 44;
Person p2;
p2.m_a = 6;
p2.m_b = 4;
Person p3;
//函数原型调用
p3 = operator+(p1,p2);
//简便调用
//p3 = p1 + p2;
cout << "p3.m_a:" << p3.m_a << endl;
cout << "p3.m_b:" << p3.m_b << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
注意两种调用方式
通过函数原型调用
p3 = operator+(p1,p2);
简便调用
p3 = p1 + p2;
运算符重载发生函数重载
运算符重载可以发生函数重载：Person+int等等
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
};
//通过全局函数实现重载
Person operator+ (Person& p1, int num)
{
//创建一个临时变量
Person temp;
temp.m_a = p1.m_a + num;
temp.m_b = p1.m_b + num;
return temp;
}
void test01()
{
Person p1;
p1.m_a = 66;
p1.m_b = 44;
Person p2;
p2.m_a = 6;
p2.m_b = 4;
Person p3;
//函数原型调用
//p3 = operator+(p1,55);
//简便调用
p3 = p1 + 55;
cout << "p3.m_a:" << p3.m_a << endl;
cout << "p3.m_b:" << p3.m_b << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
调用方法和定义方法与上面相同，不再多余赘述
总结
1、系统内置数据类型的表达式不可改变
2、不要滥用运算符重载
左移运算符
不利用成员函数重载左移运算符
没有具体演示，因为报错，我也没写出来
下面通过全局函数实现
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
};
ostream& operator<<(ostream& cout,Person&p)
{
cout << "p.m_a=" <<p. m_a << " p.m_b=" <<p. m_b << endl;
return cout;
}
void test01()
{
Person p1;
p1.m_a = 44;
p1.m_b = 66;
cout << p1 << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
因为要实现链式，实现追加，所以返回值必须是ostream
总结
配合友元实现自定义输出类型
递增运算符重载
递增运算符重载
#include<iostream>
using namespace std;
class myInt
{
friend ostream& operator<<(ostream& cout, myInt num);
public:
myInt()
{
this->m_a = 0;
}
//前置++运算符重载
myInt& operator++()//返回引用是为了一直对一个数据进行递增，否则函数默认返回一个新的数
{
//先进行++
m_a++;
//然后返回自身
return *this;
}
//后置++运算符重载
myInt operator++(int)//int表示占位参数，用于区分前置后置参数
{
//先记录当前的值
myInt temp=*this;
//再递增
m_a++;
//然后返回记录的值
return temp;
}
private:
int m_a;
};
//左移运算符重载
ostream& operator<<(ostream& cout, myInt num)
{
cout << num.m_a;
return cout;
}
void test01()
{
myInt myint;
cout << myint << endl;
cout << ++myint << endl;
cout << myint << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
赋值运算符重载
#include<iostream>
using namespace std;
class Person
{
public:
Person(int num)//将数据开辟到堆区
{
m_a = new int(num);
}
~Person()
{
if (m_a != NULL)
{
delete m_a;
m_a = NULL;
}
}
//重载赋值运算符
Person& operator=(Person &p)//返回值用Person返回本身，可执行连等
{
//先判断是否有属性在堆区，如果有先释放干净
if (m_a != NULL)
{
delete m_a;
m_a = NULL;
}
m_a = new int(*p.m_a);
return *this;
}
int* m_a;
};
void test01()
{
Person p1(18);
Person p2(209);
Person p3(9);
p2 = p1 = p3;
cout << *p1.m_a << endl;
cout << *p2.m_a << endl;
cout << *p3.m_a << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
关系运算符重载
#include<iostream>
using namespace std;
#include<string>
class Person
{
public:
Person(string name, int age)
{
this->age = age;
this->name = name;
}
bool operator==(Person& p)
{
if (this->age == p.age && this->name == p.name)
{
return true;
}
else {
return false;
}
}
bool operator!=(Person& p)
{
if (this->age == p.age && this->name == p.name)
{
return false;
}
else {
return true;
}
}
string name;
int age;
};
void test01()
{
Person p1("gouride", 19);
Person p2("gouride", 19);
if (p1 == p2) {
cout << "p1和p2相同" << endl;
}
else {
cout << "p1和p2不相同" << endl;
}
if (p1 != p2) {
cout << "p1和p2不相同" << endl;
}
else {
cout << "p1和p2相同" << endl;
}
}
int main()
{
test01();
system("pause");
return 0;
}
函数调用重载
仿函数
#include<iostream>
using namespace std;
#include<string>
class Myprint
{
public:
void operator()(string name)
{
cout << name << endl;
}
int operator()(int a,int b)
{
return a + b;
}
};
void test01()
{
Myprint myprint;
myprint("测试");
//匿名对象调用
cout << Myprint()(4,6) << endl;
}
int main()
{
test01();
system("pause");
return 0;
}
