加號運算子過載
對於內建資料型別，編譯器知道如何運算
但是對於自己封裝的類，編譯器無法進行運算
這時可以通過自己定義運算子過載進行運算
operator+
通過成員函式過載+號
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
//通過成員函式實現過載
Person operator+ (Person &p)
{
//建立一個臨時變數
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;
//通過函式原型呼叫
p3 = p1.operator+(p2);
//簡便呼叫
//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;
}
注意兩種呼叫方式
通過函式原型呼叫
p3 = p1.operator+(p2);
簡便呼叫
p3 = p1 + p2;
通過全域性函式過載+號
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
};
//通過全域性函式實現過載
Person operator+ (Person& p1, Person& p2)
{
//建立一個臨時變數
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;
//函式原型呼叫
p3 = operator+(p1,p2);
//簡便呼叫
//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;
}
注意兩種呼叫方式
通過函式原型呼叫
p3 = operator+(p1,p2);
簡便呼叫
p3 = p1 + p2;
運算子過載發生函式過載
運算子過載可以發生函式過載：Person+int等等
#include<iostream>
using namespace std;
class Person
{
public:
int m_a;
int m_b;
};
//通過全域性函式實現過載
Person operator+ (Person& p1, int num)
{
//建立一個臨時變數
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;
//函式原型呼叫
//p3 = operator+(p1,55);
//簡便呼叫
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;
}
呼叫方法和定義方法與上面相同，不再多餘贅述
總結
1、系統內建資料型別的表示式不可改變
2、不要濫用運算子過載
左移運算子
不利用成員函式過載左移運算子
沒有具體演示，因為報錯，我也沒寫出來
下面通過全域性函式實現
#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;
}
因為要實現鏈式，實現追加，所以返回值必須是ostream
總結
配合友元實現自定義輸出型別
遞增運算子過載
遞增運算子過載
#include<iostream>
using namespace std;
class myInt
{
friend ostream& operator<<(ostream& cout, myInt num);
public:
myInt()
{
this->m_a = 0;
}
//前置++運算子過載
myInt& operator++()//返回引用是為了一直對一個資料進行遞增，否則函式預設返回一個新的數
{
//先進行++
m_a++;
//然後返回自身
return *this;
}
//後置++運算子過載
myInt operator++(int)//int表示佔位引數，用於區分前置後置引數
{
//先記錄當前的值
myInt temp=*this;
//再遞增
m_a++;
//然後返回記錄的值
return temp;
}
private:
int m_a;
};
//左移運算子過載
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;
}
賦值運算子過載
#include<iostream>
using namespace std;
class Person
{
public:
Person(int num)//將資料開闢到堆區
{
m_a = new int(num);
}
~Person()
{
if (m_a != NULL)
{
delete m_a;
m_a = NULL;
}
}
//過載賦值運算子
Person& operator=(Person &p)//返回值用Person返回本身，可執行連等
{
//先判斷是否有屬性在堆區，如果有先釋放乾淨
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;
}
關係運算子過載
#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;
}
函式呼叫過載
仿函式
#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("測試");
//匿名物件呼叫
cout << Myprint()(4,6) << endl;
}
int main()
{
test01();
system("pause");
return 0;
}