c++ virtual的作用

<span style="font-family: Arial, Helvetica, sans-serif;">using namespace std;</span>

class C{public:C(){cout << "construct c" << endl;}virtual ~C(){cout << "delete c" << endl;}virtual void showc(){cout << "show c" << endl;}};class D : public  C{public:D(){cout << "construct d" << endl;}~D(){cout << "delete d" << endl;}void showd(){cout << "show d" << endl;}};int main(){C* c = new D;c->showc();delete c;return 0;}

注意：如果去掉基函数里面析构函数的virtual时候，那么D类析构的时候就调用不了~C（）造成内存泄露。所以基函数一般都默认的加virtual，起到默认的继承作用，new谁的对象，类析构的时候就调用谁的析构函数。运行结果如上图所示。