<< 运算符重写为 cout int 和 double 值

我需要重写

我想我已经包含了所有必要的部分。提前致谢。

struct Reading {
    int hour;
    double temperature;
    Reading(int h, double t): hour(h), temperature(t) { }
    bool operator<(const Reading &r) const;
};

========

ostream& operator<<(ostream& ost, const Reading &r)
{
    // unsure what to enter here

    return ost;
}

========

vector<Reading> get_temps()
{
// stub version                                                                 
    cout << "Please enter name of input file name: ";
    string name;
    cin >> name;
    ifstream ist(name.c_str());
    if(!ist) error("can't open input file ", name);

    vector<Reading> temps;
    int hour;
    double temperature;
    while (ist >> hour >> temperature){
        if (hour <0 || 23 <hour) error("hour out of range");
        temps.push_back( Reading(hour,temperature));
    }

}

例如这样：

bool operator <(Reading const& left, Reading const& right)
{
    return left.temperature < right.temperature;
}

它应该是一个全局函数（或者与Reading)，不是会员或Reading，它应该被声明为friend如果您有任何受保护或私人成员。这可以像这样完成：

struct Reading {
    int hour;
    double temperature;
    Reading(int h, double t): hour(h), temperature(t) { }

    friend bool operator <(Reading const& left, Reading const& right);
};