类(传入的形参为非指针形式)-复数的实现

 注意此处构造函数传入的参数为非指针形式，数据也是非指针形式。

#ifndef __MYCOMPLEX__
#define __MYCOMPLEX__

//定义了类——复数，作为示例，介绍了类的基本定义方式

//类以部分函数的声明
class complex; 
complex&
  __doapl (complex* ths, const complex& r);
complex&
  __doami (complex* ths, const complex& r);
complex&
  __doaml (complex* ths, const complex& r);

//定义类complex：一般类会把数据作为private的，而将一些对外的接口函数作为public的
class complex
{
public:
  //构造函数，这个地方r和i是传入的形参，后面赋值给私有成员变量re和im了
  complex (double r = 0, double i = 0): re (r), im (i) { }
  //操作符重载，扩展C++中的+=、-=、*=、/=运算符，使其可以应用在复数的运算中
  complex& operator += (const complex&);
  complex& operator -= (const complex&);
  complex& operator *= (const complex&);
  complex& operator /= (const complex&);
  //获得复数的实部和虚部
  double real () const { return re; }
  double imag () const { return im; }
private:
  double re, im;

  //友元函数，在类外也可以直接访问private成员变量
  friend complex& __doapl (complex *, const complex&);
  friend complex& __doami (complex *, const complex&);
  friend complex& __doaml (complex *, const complex&);
};

//这个函数在类中声明为友元函数了
inline complex&
__doapl (complex* ths, const complex& r)
{
  ths->re += r.re;
  ths->im += r.im;
  return *ths;
}
 
inline complex&
complex::operator += (const complex& r)
{
  //this 是这个类本身，在使用中+=左边的对象就是this
  return __doapl (this, r);
}

inline complex&
__doami (complex* ths, const complex& r)
{
  ths->re -= r.re;
  ths->im -= r.im;
  return *ths;
}
 
inline complex&
complex::operator -= (const complex& r)
{
  return __doami (this, r);
}
 
inline complex&
__doaml (complex* ths, const complex& r)
{
  double f = ths->re * r.re - ths->im * r.im;
  ths->im = ths->re * r.im + ths->im * r.re;
  ths->re = f;
  return *ths;
}

inline complex&
complex::operator *= (const complex& r)
{
  return __doaml (this, r);
}
 
//上面的函数返回的都是引用，相当于直接返回了变量地址
//下面的函数返回的都不是引用，而是局部变量的拷贝
inline double
imag (const complex& x)
{
  return x.imag ();
}

inline double
real (const complex& x)
{
  return x.real ();
}

inline complex
operator + (const complex& x, const complex& y)
{
  return complex (real (x) + real (y), imag (x) + imag (y));
}

inline complex
operator + (const complex& x, double y)
{
  return complex (real (x) + y, imag (x));
}

inline complex
operator + (double x, const complex& y)
{
  return complex (x + real (y), imag (y));
}

inline complex
operator - (const complex& x, const complex& y)
{
  return complex (real (x) - real (y), imag (x) - imag (y));
}

inline complex
operator - (const complex& x, double y)
{
  return complex (real (x) - y, imag (x));
}

inline complex
operator - (double x, const complex& y)
{
  return complex (x - real (y), - imag (y));
}

inline complex
operator * (const complex& x, const complex& y)
{
  return complex (real (x) * real (y) - imag (x) * imag (y),
               real (x) * imag (y) + imag (x) * real (y));
}

inline complex
operator * (const complex& x, double y)
{
  return complex (real (x) * y, imag (x) * y);
}

inline complex
operator * (double x, const complex& y)
{
  return complex (x * real (y), x * imag (y));
}

complex
operator / (const complex& x, double y)
{
  return complex (real (x) / y, imag (x) / y);
}

inline complex
operator + (const complex& x)
{
  return x;
}

inline complex
operator - (const complex& x)
{
  return complex (-real (x), -imag (x));
}

inline bool
operator == (const complex& x, const complex& y)
{
  return real (x) == real (y) && imag (x) == imag (y);
}

inline bool
operator == (const complex& x, double y)
{
  return real (x) == y && imag (x) == 0;
}

inline bool
operator == (double x, const complex& y)
{
  return x == real (y) && imag (y) == 0;
}

inline bool
operator != (const complex& x, const complex& y)
{
  return real (x) != real (y) || imag (x) != imag (y);
}

inline bool
operator != (const complex& x, double y)
{
  return real (x) != y || imag (x) != 0;
}

inline bool
operator != (double x, const complex& y)
{
  return x != real (y) || imag (y) != 0;
}

#include <cmath>

inline complex
polar (double r, double t)
{
  return complex (r * cos (t), r * sin (t));
}

inline complex
conj (const complex& x) 
{
  return complex (real (x), -imag (x));
}

inline double
norm (const complex& x)
{
  return real (x) * real (x) + imag (x) * imag (x);
}

#endif   //__MYCOMPLEX__