C++函数指针和类成员函数指针

一、函数指针——基本形式

char Fun(int n) { return char(n); }
//char(*pFun)(int);

void main()
{
    char(*pFun)(int);
    pFun = Fun;
    char c = (*pFun)();
    cout << c;
}

二、函数指针——typedef形式

char Fun(int n) { return char(n); }
//typedef char(*PFun)(int);
//PFun pFun;

void main()
{
    typedef char(*PFun)(int);
    PFun pFun;
    pFun = Fun;
    char c = (*pFun)();
    cout << c;
}

三、类成员函数指针

class Base
{
public:
    char Fun(int n) { return char(n); }
};

//typedef char (Base::*PFun)(int);
//PFun pFun;

void main()
{
    typedef char (Base::*PFun)(int);
    PFun pFun;
    pFun = &Base::Fun;
    Base instance;
    char c = (instance.*pFun)();
    cout << c;
}

四、类成员函数指针——类指针

class Base
{
public:
    char Fun(int n) { return char(n); }
};

//typedef char (Base::*PFun)(int);
//PFun pFun;

void main()
{
    typedef char (Base::*PFun)(int);
    PFun pFun;
    pFun = &Base::Fun;
    Base *pInstance = new Base();
    char c = (pInstance->*pFun)();
    delete pInstance;
    cout << c;
}

五、类成员函数指针——内部调用(this->*)

class Base
{
public:
    char Fun(int n) { return char(n); }
    char Fun2()
    {
        char (Base::*pFun)(int);
        pFun = &Base::Fun;
        char c = (this->*pFun)();
        return c;
    }
};

void main()
{
    Base instance;
    char c = instance.Fun2();
    cout << c;
}

六、类成员函数指针——继承调用

class Base
{
public:
    char Fun(int n) { return char(n); }

    char Fun2(int n)
    {
        //char (Base::*pFun)(int);
        //pFun = &Base::Fun;
        typedef char (Base::*PFun)(int);
        PFun pFun = &Base::Fun;
        return Proc(n, pFun);
    }

    char Proc(int n, char(Base::*pFun)(int))
    {
        return (this->*pFun)(n);
    }
};

class Derive : Base
{
public:
    char Fun(int n) { return char(n - ); }

    char Fun2(int n)
    {
        typedef char (Base::*PFun)(int);
        PFun pFun = static_cast<PFun>(&Derive::Fun);
        return Proc(n, pFun);
    }
};

void main()
{
    Base base;
    char bc = base.Fun2();
    cout << bc;

    Derive derive;
    char dc = derive.Fun2();
    cout << dc;
}

七、类成员函数指针——虚拟函数

class Base
{
public:
    void OFun() { cout << "base ordinary" << endl; }
    virtual void VFun(int i) { cout << "base virtual" << endl; }
};

class Derive : public Base
{
public:
    void OFun() { cout << "derive ordinary" << endl; }
    virtual void VFun(int i) { cout << "derive virtual" << endl; }
};

void main()
{
    typedef void (Base::*BaseOFun)();
    typedef void (Derive::*DeriveOFun)();
    BaseOFun baseOFun = &Base::OFun;
    DeriveOFun deriveOFun = static_cast<DeriveOFun>(baseOFun);

    typedef void (Base::*BaseVFun)(int);
    typedef void (Derive::*DeriveVFun)(int);
    BaseVFun baseVFun = &Base::VFun;
    DeriveVFun deriveFVun = static_cast<DeriveVFun>(baseVFun);

    Base base;
    (base.*baseOFun)();
    (base.*baseVFun)();

    Derive derive;
    (derive.*deriveOFun)();
    (derive.*deriveFVun)();
}