BoolanC++
1.基本概念
（1）C++ （c with class） ——> 面向对象程序设计
（2）基于对象：类之间没有关联面向对象：类之间有关联
（3）涉及指针、不涉及指针
（4）最常用版本c++98
（5）语言+标准库2.头文件防卫式声明
#ifndef __MYCOMPLEX__
#define __MYCOMPLEX__
前置声明类：
class complex;
全局函数：
complex& __doapl (complex* ths, const complex& r);
complex& __doami (complex* ths, const complex& r);
complex& __doaml (complex* ths, const complex& r);
类声明class complex
{
public:（public的函数是可以被外界使用的）
构造函数：
complex (double r = 0, double i = 0): re (r), im (i) { }
构造函数的函数名要和类名相同，是用来创建对象的。
参数要有默认值，叫做默认实参，否则外界调用创建对象的时候，比如complex c就没有默认值了。
构造函数不需要有返回类型，因为构造函数就是用来构造这个类的。
将传进来的参数给private的数据，采用构造函数特有的一种语法，即initialization list，用来设初值，这里是把r设到re，i设到im。不直接赋值的原因是，先要初始化再赋值，这两个步骤才是完整的，如果省掉这一步直接赋值，结论相同，但是过程不同。
外界创建对象的时候可能会有很多种写法，这样就需要不同的构造函数，c++允许构造函数重载，但是参数个数或者类型要不同以区分。常常会有构造函数重载的情况。
函数的声明：
complex& operator += (const complex&);
complex& operator -= (const complex&);
complex& operator *= (const complex&);
complex& operator /= (const complex&);
操作符重载参数complex后面有&符号，是pass by reference，是传的引用，比传value好，更快。原则是能穿引用的时候要传引用。构造函数中的double也可以传引用。函数在本体里定义：写在这里是inline函数，至于能不能实现inline看编译器。
double real () const { return re; }
double imag () const { return im; }
函数是取得复数的实部和虚部，并不会改变对象的数据，因此函数要加const。
数据封装：
private:（private的数据是class私有的，不能被外界直接使用）
double re, im;
friend complex& __doapl (complex *, const complex&);
friend complex& __doami (complex *, const complex&);
friend complex& __doaml (complex *, const complex&);
这些函数都是友元，可以直接取class里面的数据。
};
（public和private的顺序不定。）
类定义不在本体中定义：
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)
{
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);
}
inline doubleimag (const complex& x)
{
return x.imag ();
}
inline doublereal (const complex& x)
{
return x.real ();
}
inline complexoperator + (const complex& x, const complex& y)
{
return complex (real (x) + real (y),
imag (x) + imag (y));
}
inline complexoperator + (const complex& x, double y)
{
return complex (real (x) + y, imag (x));
}
inline complexoperator + (double x, const complex& y)
{
return complex (x + real (y), imag (y));
}
inline complexoperator - (const complex& x, const complex& y)
{
return complex (real (x) - real (y), imag (x) - imag (y));
}
inline complexoperator - (const complex& x, double y)
{
return complex (real (x) - y, imag (x));
}
inline complexoperator - (double x, const complex& y)
{
return complex (x - real (y), - imag (y));
}
inline complexoperator * (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 complexoperator * (const complex& x, double y)
{
return complex (real (x) * y, imag (x) * y);
}
inline complexoperator * (double x, const complex& y)
{
return complex (x * real (y), x * imag (y));
}
complexoperator / (const complex& x, double y)
{
return complex (real (x) / y, imag (x) / y);
}
inline complexoperator + (const complex& x)
{
return x;
}
inline complexoperator - (const complex& x)
{
return complex (-real (x), -imag (x));
}
inline booloperator == (const complex& x, const complex& y)
{
return real (x) == real (y) && imag (x) == imag (y);
}
inline booloperator == (const complex& x, double y)
{
return real (x) == y && imag (x) == 0;
}
inline booloperator == (double x, const complex& y)
{
return x == real (y) && imag (y) == 0;
}
inline booloperator != (const complex& x, const complex& y)
{
return real (x) != real (y) || imag (x) != imag (y);
}
inline booloperator != (const complex& x, double y)
{
return real (x) != y || imag (x) != 0;
}
inline booloperator != (double x, const complex& y)
{
return x != real (y) || imag (y) != 0;
}
#includeinline complexpolar (double r, double t)
{
return complex (r * cos (t), r * sin (t));
}
inline complexconj (const complex& x)
{
return complex (real (x), -imag (x));
}
inline doublenorm (const complex& x)
{
return real (x) * real (x) + imag (x) * imag (x);
}
结束防卫式声明#endif //__MYCOMPLEX__
3.主函数
#include
#include "complex.h"
using namespace std;
ostream&
operator << (ostream& os, const complex& x)
{
return os << '(' << real (x) << ',' << imag (x) << ')';
}
int main()
{
complex c1(2, 1);
complex c2(4, 0);
cout << c1 << endl;
cout << c2 << endl;
cout << c1+c2 << endl;
cout << c1-c2 << endl;
cout << c1*c2 << endl;
cout << c1 / 2 << endl;
cout << conj(c1) << endl;
cout << norm(c1) << endl;
cout << polar(10,4) << endl;
cout << (c1 += c2) << endl;
cout << (c1 == c2) << endl;
cout << (c1 != c2) << endl;
cout << +c2 << endl;
cout << -c2 << endl;
cout << (c2 - 2) << endl;
cout << (5 + c2) << endl;
return 0;
}