# C++全面细致讲解复数类

• 运算：+，- ，*，/
• 比较：== ，! =
• 赋值：=
• 求模：modulus

## 二、利用操作符重载

Complex.h：

```#ifndef _COMPLEX_H_
#define _COMPLEX_H_
class Complex
{
double a;
double b;
public:
Complex(double a = 0, double b = 0);
double getA();
double getB();
double getModulus();
Complex operator + (const Complex& c);
Complex operator - (const Complex& c);
Complex operator * (const Complex& c);
Complex operator / (const Complex& c);
bool operator == (const Complex& c);
bool operator != (const Complex& c);
Complex& operator = (const Complex& c);
};
#endif```

Complex.cpp：

```#include "Complex.h"
#include "math.h"
Complex::Complex(double a, double b)
{
this->a = a;
this->b = b;
}
double Complex::getA()
{
return a;
}
double Complex::getB()
{
return b;
}
double Complex::getModulus()
{
return sqrt(a * a + b * b);
}
Complex Complex::operator + (const Complex& c)
{
double na = a + c.a;
double nb = b + c.b;
Complex ret(na, nb);
return ret;
}
Complex Complex::operator - (const Complex& c)
{
double na = a - c.a;
double nb = b - c.b;
Complex ret(na, nb);
return ret;
}
Complex Complex::operator * (const Complex& c)
{
double na = a * c.a - b * c.b;
double nb = a * c.b + b * c.a;
Complex ret(na, nb);
return ret;
}
Complex Complex::operator / (const Complex& c)
{
double cm = c.a * c.a + c.b * c.b;
double na = (a * c.a + b * c.b) / cm;
double nb = (b * c.a - a * c.b) / cm;
Complex ret(na, nb);
return ret;
}
bool Complex::operator == (const Complex& c)
{
return (a == c.a) && (b == c.b);
}
bool Complex::operator != (const Complex& c)
{
return !(*this == c);
}
Complex& Complex::operator = (const Complex& c)
{
if( this != &c )
{
a = c.a;
b = c.b;
}
return *this;
}```

test.cpp：

```#include
#include "Complex.h"
int main()
{
Complex c1(1, 2);
Complex c2(3, 6);
Complex c3 = c2 - c1;
Complex c4 = c1 * c3;
Complex c5 = c2 / c1;
printf("c3.a = %f, c3.b = %f\n", c3.getA(), c3.getB());
printf("c4.a = %f, c4.b = %f\n", c4.getA(), c4.getB());
printf("c5.a = %f, c5.b = %f\n", c5.getA(), c5.getB());
Complex c6(2, 4);
printf("c3 == c6 : %d\n", c3 == c6);
printf("c3 != c4 : %d\n", c3 != c4);
(c3 = c2) = c1;
printf("c1.a = %f, c1.b = %f\n", c1.getA(), c1.getB());
printf("c2.a = %f, c2.b = %f\n", c2.getA(), c2.getB());
printf("c3.a = %f, c3.b = %f\n", c3.getA(), c3.getB());
return 0;
}```

## 三、注意事项

• C++ 规定赋值操作符（=）只能重载为成员函数
• 操作符重载不能改变原操作符的优先级
• 操作符重载不能改变操作数的个数
• 操作符重载不应改变操作符的原有语义

## 四、小结

• 复数的概念可以通过自定义类实现
• 复数中的运算操作可以通过操作符重载实现
• 赋值操作符只能通过成员函数实现
• 操作符重载的本质为函数定义