C++ 多态案例（一）- 计算器类

//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;}