C++ 0x问题:将时间插入到std :: set中

#include<iostream>
#include <set>
#include <ctime>

class Time {
public:
    Time() {
        time_t now = std::time(nullptr);
        tm = std::localtime(&now);
    }

    bool operator<(const Time& other) const {
        return std::mktime(tm) < std::mktime(other.tm);
    }

    friend std::ostream& operator<<(std::ostream& os, const Time& time) {
        os<< std::asctime(time.tm);
        return os;
    }

private:
    std::tm* tm;
};

int main() {
    std::set<Time> times;

    for (int i = 0; i < 10; ++i) {
        times.insert(Time());
    }

    for (const auto& time : times) {
        std::cout<< time<< std::endl;
    }

    return 0;
}