c++ - ostream 的重载 << 运算符，用于虚函数

Question

我已经 overloaded << opreator这样:

ostream& operator<<(ostream&os, const Computer& c) {
     for (int i = 0; i != c.listOfComponents.size() - 1; i++) {
        os << c.listOfComponents[i].getInfo(os) << endl;    
    }
    return os;
}

哪里listoOfComponents是vector<Component> .

我的 Component类和其中一个子类在这里:

class Component {
public:

    Component() {
    };

    ~Component() {
    };

  virtual ostream &getInfo(ostream& os)const;
};

ostream &Component::getInfo(ostream& os)const {
    return os;
}

class CPU : public Component {
public:

    CCPU(int cores, int freq) {
        this->cores = cores;
        this->freq = freq;
    };

    ~CPU() {
    };

    virtual ostream &getInfo(ostream& os)const;

    int cores;
    int freq;
};

ostream &CPU::getInfo(ostream& os)const {
        os<<"CORES:"<<cores<<" FREQ:"<<freq<<endl;
 }

最后是 Computer类:

class Computer {
public:
    // constructor

    Computer(string name) {
        this->name = name;
    };
    // destructor

    ~Computer() {

    };


    // operator <<
    friend ostream& operator<<(ostream& os, const CComputer& c);

    CComputer & AddComponent(Component const & component) {
        this->listOfComponents.push_back(component);
        return *this;
    };

    CComputer & AddAddress(const string & address) {
        this->address = address;
        return *this;
    };

    string name;
    string address;
    vector<Component> listOfComponents;
};

但是，当我想通过 cout<<os; 打印出来时它只打印出地址(即 0x6c180484)。但我不知道如何编写它才能编译它并获得正确的值...

Answer 1

首先，为什么打印到流的方法叫做get_info ？叫它put_info() (具有相同的返回类型/参数)并像使用它一样

c.listOfComponents.put_info(os) << endl;

不要忘记从 put_info 返回流.

在你这样做之后，它仍然不起作用，因为vector<Component>恰好包含组件——如果你按下一个 CPU中，它被残酷地截断为 Component .