1 //多态案例 -计算器类（普通写法  和 多态写法）

  2

  3 #include <iostream>

  4 #include <string>

  5 using namespace std;

  6

  7 //普通实现

  8 class Calualtor

  9 {

 10 public:

 11

 12     int getResult(string oper)

 13     {

 14         if (oper == "+")

 15         {

 16             return m_Num1 + m_Num2;

 17         }

 18         else if (oper == "-")

 19         {

 20             return m_Num1 - m_Num2;

 21         }

 22         else if (oper == "*")

 23         {

 24             return m_Num1 * m_Num2;

 25         }

 26         //如果想扩展新的功能，需要修改源码

 27         //在真实的开发中   提倡 开闭原则

 28         //开闭原则：对扩展进行开放  对修改进行关闭

 29     }

 30

 31

 32     int m_Num1;   //操作数1

 33     int m_Num2;   //操作数2

 34 };

 35

 36 void test01()

 37 {

 38     //创建计算器的对象

 39     Calualtor c;

 40     c.m_Num1 = 10;

 41     c.m_Num2 = 10;

 42

 43     cout << c.m_Num1 << "+" << c.m_Num2 << "=" << c.getResult("+") << endl;

 44

 45     cout << c.m_Num1 << "-" << c.m_Num2 << "=" << c.getResult("-") << endl;

 46

 47     cout << c.m_Num1 << "*" << c.m_Num2 << "=" << c.getResult("*") << endl;

 48 }

 49

 50

 51 //利用多态实现计算器

 52 //多态好处：

 53 //1.组织结构清晰

 54 //2.可读性强

 55 //3.对于前期和后期扩展以及维护性高

 56

 57

 58 //实现计算器的抽象类

 59 class AbstractCalculator

 60 {

 61 public:

 62

 63     virtual int getResult()

 64     {

 65         return 0;

 66     }

 67

 68     int m_Num1;

 69     int m_Num2;

 70 };

 71

 72 //加法计算器

 73 class AddCalculator : public AbstractCalculator

 74 {

 75

 76 public:

 77     virtual int getResult()

 78     {

 79         return m_Num1 + m_Num2;

 80     }

 81 };

 82

 83 //减法计算器

 84 class SubCalculator : public AbstractCalculator

 85 {

 86

 87 public:

 88     virtual int getResult()

 89     {

 90         return m_Num1 - m_Num2;

 91     }

 92 };

 93 //乘法计算器

 94 class MulCalculator : public AbstractCalculator

 95 {

 96

 97 public:

 98     virtual int getResult()

 99     {

100         return m_Num1 * m_Num2;

101     }

102 };

103

104

105 void test02()

106 {

107     //多态使用条件

108

109     //父类指针或者引用指向子类对象

110     //加法运算

111     AbstractCalculator* abc = new  AddCalculator;

112     abc->m_Num1 = 10;

113     abc->m_Num2 = 20;

114     cout << "多态计算器" << endl;

115     cout << abc->m_Num1 << "+" << abc->m_Num2 << "=" << abc->getResult() << endl;

116

117     //用完后销毁

118     delete abc;

119

120     //减法运算

121     abc = new SubCalculator;

122     abc->m_Num1 = 100;

123     abc->m_Num2 = 101;

124     cout << abc->m_Num1 << "-" << abc->m_Num2 << "=" << abc->getResult() << endl;

125     delete abc;

126

127     abc = new MulCalculator;

128     abc->m_Num1 = 12;

129     abc->m_Num2 = 10;

130     cout << abc->m_Num1 << "*" << abc->m_Num2 << "=" << abc->getResult() << endl;

131

132     delete abc;

133 }

134

135 int main()

136 {

137

138     test01();

139

140     test02();

141

142     system("pause");

143

144     return 0;

145

146 }