C++簡單工廠模式

核心思想：用一個工廠類根據不同的輸入條件new出不同的派生類指針，然后由多態調用不同派生類中virtual函數，得到不同的結果

所有的判斷處理在工廠類中完成，通過CreateFactory函數，根據不同的類型，new出派生類指針，返回基類指針。

代碼如下：

class CFactory
{
public:
    CFactory(void);
    ~CFactory(void);

public:
    static IOperator* CreateFactory(char cStr);
};

IOperator* CFactory::CreateFactory(char cStr)
{
    IOperator *pStr = NULL;
    switch(cStr)
    {
    case '+':
        {
            pStr = new CAddOperator();
        }
        break;
    case '-':
        {
            pStr = new CSubtract();
        }
        break;
    default:
        break;
    }

    return pStr;
}

class IOperator
{
public:
    IOperator(void);
    virtual ~IOperator(void);

public:
    virtual int Result() = 0;

public:
    int m_nA;
    int m_nB;
};

class CAddOperator : public IOperator
{
public:
    CAddOperator(void);
    ~CAddOperator(void);

public:
    virtual int Result();
};

class CSubtract : public IOperator
{
public:
    CSubtract(void);
    ~CSubtract(void);

public:
    virtual int Result();
};

外部調用：
    IOperator *pTemp = CFactory::CreateFactory('+');
    if (NULL != pTemp)
    {
        pTemp->m_nA = 4;
        pTemp->m_nB = 3;

        int i = pTemp->Result();
    }

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