Question

我将A类纳入C中包含的B女巫中。

在A班我有一个ExamItemStates函数。我可以从B级访问它： ExamItemStates函数声明为Public：

BOOL ExamItemStates(int nItem, DWORD dwStates) const;

B级标题：

class B : public CDialogEx
{
    DECLARE_DYNAMIC(B)
public:
    B(CWnd* pParent = NULL);   // standard constructor
    enum { IDD = IDD_B };
    CReportCtrl m_wndList;
protected:
    virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
    virtual BOOL OnInitDialog();
    DECLARE_MESSAGE_MAP()
};
//B.cpp
    void B::DoDataExchange(CDataExchange* pDX)
    {
        DDX_Control(pDX, IDC_LIST1, m_wndList);
        CDialogEx::DoDataExchange(pDX);
    }
    BOOL B::OnInitDialog()
    {
        CDialogEx::OnInitDialog();

        if (m_wndList.ExamItemStates(2, RC_ITEM_CHECKED))
            AfxMessageBox(L"Please write correct name!");
        UpdateData(FALSE);

        return TRUE;
    }

我需要从C级访问它。我怎么能这样做？

Answer 1

尝试使用protected代替private，方法一般应为public:：例如

class Foo
{
protected:
    int a, b;
public:
    void Method1();
};

提供您的头文件（带有类的文件）以获得更多解释。

这是可导出类的典型方案：

class Foo
{
private:
    // elements that cannot be inherited (you cannot use them in the child classes) and cannot be accessed from outside of the class
protected:
    // elements that can be inherited, but cannot be accessed from outside of the class
public:
    // elements that can be inherited and accessed outside the class
};

示例代码：

class A
{
protected:
    void DerivableMethod();
private:
    int AccessibleOnlyInClassA;
};

class B : public A
{
protected:
    void AnotherProtectedMethod();
private:
    int AccessibleOnlyInClassB;
};

class C : public B
{
public:
    void MethodInClasC()
    {
        DerivableMethod();
    }
};

如何访问会员？ MFC

1 个答案: