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;
}
总结
到此这篇关于C++运算符重载的文章就介绍到这了,更多相关C++运算符重载内容请搜索软件开发网以前的文章或继续浏览下面的相关文章希望大家以后多多支持软件开发网！