将分钟::rep 转换为小时::rep

Question

我应该如何继续将std::chrono::minutes::rep 类型值转换为小时表示。

#include <iostream>
#include <chrono>

using namespace std;
using namespace std::chrono;

int main() {
    minutes::rep time = 4;
    std::cout << time;  // outputs as minutes, need in hours

    // duration cast doesn't seems to work here because it
    // needs minutes instead of minutes::rep probably

    return 0;
}

Answer 1

minutes::rep time = 4;
std::cout << time;  // outputs as minutes, need in hours

因为time 只是一个（实现定义的）整数类型，它与minutes 或hours 无关，并且对底层时间表示一无所知。

你想留在duration领域：

minutes time{4};
auto as_hours = std::duration_cast<hours>(time);
std::cout << as_hours.count(); // prints 0

或者，可能：

auto as_hours_dbl = std::duration_cast<duration<double, hours::period>>(time);
std::cout << as_hours_dbl.count(); // prints 0.0666667