操作符重载03--和/差/积/商赋值运算符（Sum Assignment Operator）

+=、-=、*=、/=操作符重载。

测试类.h

#pragma once

/*和/差/积/商赋值操作符重载
1. 为2元操作符
2. 一般返回类的引用，其实作为成员函数不返回值也可以，就是this本身
3. 注意要满足运算符有意义，尤其是除法
*/
class TRectangle
{
    friend TRectangle operator+(const TRectangle& x, const TRectangle& y);
    friend TRectangle operator-(const TRectangle& x, const TRectangle& y);
    friend TRectangle operator*(const TRectangle& x, const TRectangle& y);
    friend TRectangle operator/(const TRectangle& x, const TRectangle& y);
public:
    TRectangle(double L = 0.00, double H = 0.00);
    TRectangle(const TRectangle& R);
    ~TRectangle();

    //method
    void setLength(const double L) { Length = L; }
    double getLength() const { return Length; }
    void setHeight(const double H) { Height = H; }
    double getHeight() const { return Height; }
    double Perimeter() const { return 2 * (Length + Height); }
    double Area() const { return Length * Height; }

    TRectangle& operator=(const TRectangle& Rect);

    TRectangle& operator+=(const TRectangle& Rect);
    TRectangle& operator-=(const TRectangle& Rect);
    TRectangle& operator*=(const TRectangle& Rect);
    TRectangle& operator/=(const TRectangle& Rect);
private:
    double Length;
    double Height;
};

测试类.cpp

   1: #include "StdAfx.h"

   2: #include "TRectangle.h"

   3:  

   4:  

   5: TRectangle::TRectangle(double L, double H) : 

   6: Length(L),

   7: Height(H)

   8: {

   9: }

  10:  

  11: TRectangle::TRectangle(const TRectangle& R) :

  12: Length(R.Length),

  13: Height(R.Height)

  14: {

  15: }

  16:  

  17: TRectangle::~TRectangle(void)

  18: {

  19: }

  20:  

  21: TRectangle& TRectangle::operator=(const TRectangle& Rect)

  22: {

  23:     Length = Rect.Length;

  24:     Height = Rect.Height;

  25:     return *this;

  26: }

  27:  

  28: TRectangle operator+(const TRectangle& x, const TRectangle& y)

  29: {

  30:     TRectangle R;

  31:     R.Length = x.Length + y.Length;

  32:     R.Height = x.Height + y.Height;

  33:     return R;

  34: }

  35:  

  36: TRectangle operator-(const TRectangle& x, const TRectangle& y)

  37: {

  38:     TRectangle R;

  39:     R.Length = x.Length - y.Length;

  40:     R.Height = x.Height - y.Height;

  41:  

  42:     return R;

  43: }

  44:  

  45: TRectangle operator*(const TRectangle& x, const TRectangle& y)

  46: {

  47:     TRectangle R;

  48:     R.Length = x.Length * y.Length;

  49:     R.Height = x.Height * y.Height;

  50:  

  51:     return R;

  52: }

  53:  

  54: TRectangle operator/(const TRectangle& x, const TRectangle& y)

  55: {

  56:     TRectangle R;

  57:     if( y.Length == 0 ) // 避免分母为0

  58:         R.Length = 0;

  59:     else

  60:         R.Length = x.Length / y.Length;

  61:  

  62:     if( y.Height == 0 )

  63:         R.Height = 0;

  64:     else

  65:         R.Height = x.Height / y.Height;

  66:  

  67:     return R;

  68: }

  69:  

  70: TRectangle& TRectangle::operator+=(const TRectangle& R)

  71: {

  72:     Length += R.Length;

  73:     Height += R.Height;

  74:  

  75:     return *this;

  76: }

  77:  

  78: TRectangle& TRectangle::operator-=(const TRectangle& R)

  79: {

  80:     Length -= R.Length;

  81:     Height -= R.Height;

  82:  

  83:     return *this;

  84: }

  85:  

  86: TRectangle& TRectangle::operator*=(const TRectangle& R)

  87: {

  88:     Length *= R.Length;

  89:     Height *= R.Height;

  90:  

  91:     return *this;

  92: }

  93:  

  94: TRectangle& TRectangle::operator/=(const TRectangle& R)

  95: {

  96:     if( R.Length == 0 )

  97:         Length = 0;

  98:     else

  99:         Length /= R.Length;

 100:  

 101:     if( R.Height == 0 )

 102:         Height = 0;

 103:     else

 104:         Height /= R.Height;

 105:  

 106:     return *this;

 107: }

main

   1: // SumAssignmentOperator.cpp : 定义控制台应用程序的入口点。

   2: //

   3:  

   4: #include "stdafx.h"

   5: #include <iostream>

   6: #include "TRectangle.h"

   7: using namespace std;

   8:  

   9: void ShowResult(TRectangle& R, char* str = "")

  10: {

  11:     cout << str << "  Length : " << R.getLength() << " Height : " << R.getHeight() << endl;

  12: }

  13:  

  14: int _tmain(int argc, _TCHAR* argv[])

  15: {

  16:     TRectangle Ra, Rb, Rc;

  17:     Ra.setLength(20);

  18:     Ra.setHeight(10);

  19:  

  20:     Rb.setLength(40);

  21:     Rb.setHeight(20);

  22:  

  23:     ShowResult(Ra, "Ra");

  24:     ShowResult(Rb, "Rb");

  25:  

  26:     Rc = Ra;

  27:     ShowResult(Rc, "Rc Initialize");

  28:  

  29:     Rc += Rb;

  30:     ShowResult(Rc, "Rc += Rb");

  31:  

  32:     Rc -= Rb;

  33:     ShowResult(Rc, "Rc -= Rb");

  34:  

  35:     Rc *= Rb;

  36:     ShowResult(Rc, "Rc *= Rb");

  37:  

  38:     Rc /= Rb;

  39:     ShowResult(Rc, "Rc /= Rb");

  40:  

  41:     return 0;

  42: }

  43:  

测试结果图