簡單工廠模式

前序:

請用一種面向對象的語言來實現一個計算器控制臺程序,要求輸入兩個數和運算符并得到結果

簡單工廠模式:

從設計模式的類型上來說，簡單工廠模式是屬于創建型模式，又叫做靜態工廠方法（StaticFactory Method）模式，但不屬于23種GOF設計模式之一。簡單工廠模式是由一個工廠對象決定創建出哪一種產品類的實例。簡單工廠模式是工廠模式家族中最簡單實用的模式，可以理解為是不同工廠模式的一個特殊實現。

實現方式(UML類圖):

實現代碼:

#include <stdio.h>

class Operation

{

public:

       double NumberA;

       double NumberB;

       virtual double GetResult()

       {

              return 0;

       }

};

class OperationAdd : public Operation

{

public:

       virtual double GetResult()

       {

              return NumberA + NumberB;

       }

};

class OperationSub : public Operation

{

public:

       virtual double GetResult()

       {

              return NumberA - NumberB;

       }

};

class OperationMul : public Operation

{

public:

       virtual double GetResult()

       {

              return NumberA * NumberB;

       }

};

class OperationDiv : public Operation

{

public:

       virtual double GetResult()

       {

              if(NumberB == 0) return 0;

              return NumberA / NumberB;

       }

};

class OperationFactory

{

public:

       static Operation* createOperate(char operate)

       {

              Operation* oper = 0;

              switch(operate)

              {

                     case '+':

                            oper = new OperationAdd();

                            break;

                     case '-':

                            oper = new OperationSub();

                            break;

                     case '*':

                            oper = new OperationMul();

                            break;

                     case '/':

                            oper = new OperationDiv();

                            break;

              }

              return oper;

       }

};

int main()

{

       Operation* oper = OperationFactory::createOperate('+');

       oper->NumberA = 1;

       oper->NumberB = 2;

       printf("%f",oper->GetResult());

       delete oper;

       return 0;

}

運行結果:

3.0000