C++基于对象--Class without pointer

要注意培养正规的、大气的编程习惯。

1、基于对象（Object Based）：面向单一class的设计。

    class有两种经典的分类：

    一种不带有指针

    另一种带有指针

2、面向对象（Object Oriented）：面对的是多重classes的设计，classes和classes之间的关系。

    -继承 

    -复合 

    -委托

3、推荐书籍

本文所谈的对象是不带有指针的类（Class without pointer）；

具体的分析了类的组成，重点介绍类方法的设计准则；

主要是内联函数，参数传递，返回值传递，友元函数以及操作符重载在类设计中的使用。

下面的示例程序来自于--侯捷老师的网络课程《C++面向对象高级开发》。

通过程序及注释详细的介绍Class without pointer的设计。

complex.h

//写在前面//1.关于内联函数：//  如果函数在body内定义，这样便成为了inline的候选人。//  如果在body之外定义，默认不是inline函数。需要在函数的前面加inline关键字。//  在声明时写不写inline没有影响，建议不写。//  是否真的成为inline函数，最终由编译器决定。//2.不带指针的类多半不用自己写析构函数。//3.参数传递//  值传递：尽量不要使用值传递，不然会出现大量的拷贝。//  引用传递：相当于传指针，速度很快。//  const引用，保证传进去的值不会被修改。//4.返回值传递//  尽量传递引用，局部变量不能作为引用返回。//5.friend友元函数//  可以直接读取对象内部的私有成员；//  相同class的各个objects互为friends；//  友元会破坏类的封装性，不宜多用。//防卫式声名头文件#ifndef __MYCOMPLEX__#define __MYCOMPLEX__class complex;complex&__doapl(complex* ths, const complex& r);complex&__doami(complex* ths, const complex& r);complex&__doaml(complex* ths, const complex& r);class complex{public://最好使用初始化列表的方式进行初始化，比起在函数体内进行赋值，效率会高。complex(double r = 0, double i = 0) : re(r), im(i) { }complex& operator += (const complex&);complex& operator -= (const complex&);complex& operator *= (const complex&);//常量成员函数,不改变对象内的数据。double real() const { return re; } double imag() const { return im; }//数据一定放在private里面private:double re, im;friend complex& __doapl(complex *, const complex&);friend complex& __doami(complex *, const complex&);friend complex& __doaml(complex *, const complex&);};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;}#include <cmath>inline 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);}#include <iostream>using namespace std;ostream&operator << (ostream& os, const complex& x){return os << '(' << real(x) << ',' << imag(x) << ')';}#endif   //__MYCOMPLEX__

complex-test.cpp

#include "complex.h"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;}