多态案例一-计算器类
案例描述：
分别利用普通写法和多态技术，设计实现两个操作数进行运算的计算器类
多态的优点：
代码组织结构清晰
可读性强
利于前期和后期的扩展以及维护
示例：
//普通实现
class Calculator {
public:
int getResult(string oper)
{
if (oper == "+") {
return m_Num1 + m_Num2;
}
else if (oper == "-") {
return m_Num1 - m_Num2;
}
else if (oper == "*") {
return m_Num1 * m_Num2;
}
//如果要提供新的运算，需要修改源码
}
public:
int m_Num1;
int m_Num2;
};
void test01()
{
//普通实现测试
Calculator c;
c.m_Num1 = 10;
c.m_Num2 = 10;
cout << c.m_Num1 << " + " << c.m_Num2 << " = " << c.getResult("+") << endl;
cout << c.m_Num1 << " - " << c.m_Num2 << " = " << c.getResult("-") << endl;
cout << c.m_Num1 << " * " << c.m_Num2 << " = " << c.getResult("*") << endl;
}
int main() {
test01();
system("pause");
return 0;
}
//多态实现
//抽象计算器类
//多态优点：代码组织结构清晰（哪里出问题直接定位），可读性强，利于前期和后期的扩展（想添加什么功能直接添加相关类）以及维护（哪里出问题直接定位，一个功能出问题不影响其他功能）
class AbstractCalculator
{
public :
virtual int getResult()
{
return 0;
}
int m_Num1;
int m_Num2;
};
//加法计算器
class AddCalculator :public AbstractCalculator
{
public:
int getResult()
{
return m_Num1 + m_Num2;
}
};
//减法计算器
class SubCalculator :public AbstractCalculator
{
public:
int getResult()
{
return m_Num1 - m_Num2;
}
};
//乘法计算器
class MulCalculator :public AbstractCalculator
{
public:
int getResult()
{
return m_Num1 * m_Num2;
}
};
void test02()
{
//创建加法计算器
AbstractCalculator *abc = new AddCalculator;
abc->m_Num1 = 10;
abc->m_Num2 = 10;
cout << abc->m_Num1 << " + " << abc->m_Num2 << " = " << abc->getResult() << endl;
delete abc; //用完了记得销毁
//创建减法计算器
abc = new SubCalculator;
abc->m_Num1 = 10;
abc->m_Num2 = 10;
cout << abc->m_Num1 << " - " << abc->m_Num2 << " = " << abc->getResult() << endl;
delete abc;
//创建乘法计算器
abc = new MulCalculator;
abc->m_Num1 = 10;
abc->m_Num2 = 10;
cout << abc->m_Num1 << " * " << abc->m_Num2 << " = " << abc->getResult() << endl;
delete abc;
}
int main() {
//test01();
test02();
system("pause");
return 0;
}
多态优点：代码组织结构清晰（哪里出问题直接定位），可读性强，利于前期和后期的扩展（想添加什么功能直接添加相关类）以及维护（哪里出问题直接定位，一个功能出问题不影响其他功能）
总结：C++开发提倡利用多态设计程序架构，因为多态优点很多