C/C++ 虚析构函数

虚析构函数是为了解决基类指针指向派生类对象，并用基类指针delete派生类对象，导致的内存泄漏问题。

class Base
{
public:
    Base(){
        a = 1;
    }
    // 1）
    virtual ~Base()
    {
        cout << "destruct base." << endl;
    }
    // 2）
    ~Base()
    {
        cout << "destruct base." << endl;
    }
private:
    int a;
};

class Derived : public Base
{
public:
    Derived(){
        b = 2;
    }
    ~Derived()
    {
        cout << "destruct derived." << endl;
    }
private:
    int b;
};

Base *bp = new Derived;
delete bp;

输出：
1）动态绑定，先调用~Derived()，再调用~Base()
destruct derived.
destruct base.

2）静态绑定，调用~Base()，int b没释放
destruct base.