第三十一课 复数类

第三十一课 复数类

一、复数类的操作符

• 运算

  +、-、*、/

• 比较

  ==、!=

• 赋值

  =

• 求模

  modulus

二、目的

• 利用操作符的重载统一复数的实数运算方式以及实数的比较方式

做一个复数类

complex.h

#ifndef __COMPLEX_H_
#define __COMPLEX_H_
class complex
{
private:
    /* data */
    double a;
    double b;
public:
    complex(double a = 0, double b = 0);
    ~complex();
    double getA(void);
    double getB(void);
    double getModulus(void);

    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.c

#include "complex.h"
#include <math.h>
complex::complex(double a, double b)
{
    this->a = a;
    this->b = b;
}

double complex::getA(void)
{
    return a;
}

double complex::getB(void)
{
    return b;
}
double complex::getModulus(void)
{
    return sqrtf(a * a + b * b);
}

complex complex::operator + (const complex& c)
{
    complex ret;

    ret.a = a + c.a;
    ret.b = b + c.b;
    return ret;
}
complex complex::operator - (const complex& c)
{
    complex ret;

    ret.a = a - c.a;
    ret.b = b - c.b;
    return ret;
}
complex complex::operator * (const complex& c)
{
    complex ret;

    ret.a = a * c.a - b * c.b;
    ret.b = b * c.a + a * c.b;
    return ret;
}
complex complex::operator / (const complex& c)
{
    complex ret;

    ret.a = (a * c.a + b * c.b) / (c.a * c.a + c.b * c.b);
    ret.b = (b * c.a - a * c.b) / (c.a * c.a + c.b * c.b);
    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;
}
complex::~complex()
{
}

test.c

#include "complex.h"
#include <stdio.h>

int main()
{
    complex t1(1, 2);
    complex t2(3, 4);
    complex t3 = t2 + t1;

    printf("%f %f\n", t3.getA(), t3.getB());
}

执行结果

4.000000 6.000000

三、注意事项

• C++ 规定的赋值操作符（=）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