C++继承练习3

参考资料：《C++Primer习题集（第5版）》

目的：理解每个print函数的机制。
话说这感觉有点儿像打草稿。。。

#include 
#include 
#include 
#include 
using namespace std;

//class Base {
//  public:
//      string name() const {return basename;}
//      virtual void print(ostream &os) {os << basename;}
//  private:
//      string basename = "xyz";
//};
/*
class Derived : public Base {
    public:
        void print(ostream &os) {os << "xyz" << endl; print(os); os << " " << mem;}//没有声明Derived是从Base派生过来的;
    private:
        int mem;
};
*/

class Base {
    public:
        Base(string s) : basename(s) {}//初始化构造器;
        string name() const {return basename;}
        virtual void print(ostream &os) {os << basename << endl;}
    private:
        string basename;
};

class Derived : public Base {
    public:
        Derived(string s, int ival) : Base(s), mem(ival) {}//调用基类的构造函数;
        void print() {Base::print(cout); cout << mem << endl;}//声明Derived是从Base派生过来的;
    private:
        int mem;
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    Base *b = new Base("ab");
    b -> print(cout);//xyz;
    Derived *d = new Derived("cd", 12);
    d -> print();
    delete b;
    delete d;
    return 0;
}