Friday, June 12, 2015

Can I call a virtual function from ctor in C++?


Yes, but be careful. Actually, never call a virtual function in ctor or dtor.
@ the answer form the author of C++


@http://hilite.me/

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#include <iostream>

using namespace std;

class Shape {
public:
    virtual void draw() {
        cout << "draw a Shape." << endl;
    }
};

class Circle : public Shape {
public:
    void draw() {
        cout << "draw a Circle." << endl;
    }
};


class Base {
public:
    Base() {
        cout << "Base()" <<endl;

        f();
        
        Shape* shape = new Circle;
        shape->draw();
    }

    virtual void f() {
        cout << "Base::f()" << endl;
    }
};

class Derive : public Base {
public:
    Derive() {
        cout << "Derive()" << endl;
    }

    void f() {
        cout << "Derive::f()" << endl;
    }
};


int main()
{
    Base* b = new Derive;
    
    return 0;
}


Base::f()
draw a Circle.
Derive()
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