运算符重载

浅浅的花香味﹌ 2022-04-10 07:23 289阅读 0赞

***运算符重载函数作为成员函数***

class Complex {
    public:
    	Complex() { 
    		real = 0.0, imag = 0.0;
    	}
    	Complex(double real, double imag) {
    		this->real = real;
    		this->imag = imag;
    	}
    	Complex operator+ (Complex &c2);
    	void display();
    private:
    	double real,imag;
    };
    //运算符重载函数定义：
    Complex Complex::operator+(Complex &c2) {
    	Complex c;
    	c.real = real + c2.real;
    	c.imag = imag + c2.imag;
    	return c;
    	//return(Complex(real+c2.real,imag+c2.imag)）;//这样比较简便
    }
    void Complex::display() {
    	cout << real << "+" << imag << "i" << endl;
    }
    
    int main() {	
    	Complex c1(3, 1);
    	Complex c2(4, 4);
    	Complex c = c1 + c2;
    	c.display();
    	system("pause");		
    }

## 解读 ##

**1 运算符的重载实质上函数的重载。**  
c1 + c2相当于c1.operator+(c2)，这里operator+是一个函数名。

## 不允许重载的运算符 ##

<table> 
 <thead> 
  <tr> 
   <th>成员访问运算符</th> 
   <th>成员指针访问运算符</th> 
   <th>域运算符</th> 
   <th>长度运算符</th> 
   <th>条件运算符</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>.</td> 
   <td>*</td> 
   <td>：：</td> 
   <td>sizeof</td> 
   <td>？：</td> 
  </tr> 
 </tbody> 
</table>

***运算符重载函数作为友元类函数（效果与上面相同）***

class Complex {
    public:
    	Complex() { 
    		real = 0.0, imag = 0.0;
    	}
    	Complex(double real, double imag) {
    		this->real = real;
    		this->imag = imag;
    	}
    	friend Complex operator+ (Complex &c1, Complex &c2);
    	void display();
    private:
    	double real,imag;
    };
    void Complex::display() {
    	cout << real << "+" << imag << "i" << endl;
    }
    Complex operator+ (Complex &c1, Complex &c2) {
    	return Complex(c1.real + c2.real, c1.imag + c2.imag);
    }
    int main() {	
    	Complex c1(3, 1);
    	Complex c2(4, 4);
    	Complex c = c1 + c2;
    	c.display();
    	system("pause");		
    }

c1+c2相当于operator+(c1,c2)。

## 总结 ##

如果作为成员函数，他可以通过this指针自由地访问本类的数据成员，因此可以少些一个函数的参数。作为友元函数，则函数的参数列表中必须有两个参数，不能省略