cpp chrono basic

// cpp 20

//c++ - Number of seconds since midnight - Stack Overflow

//https://stackoverflow.com/questions/61273498/number-of-seconds-since-midnight

int main(int argc, char** argv)

{

    std::system("chcp 65001");

    using namespace std;

    using namespace std::chrono;

    // chrono time point to string

    auto chronoNow = chrono::system_clock::now();

    cout << chronoNow << endl;

    std::time_t tt = chrono::system_clock::to_time_t(chronoNow);

    char buffer[32];

    std::tm ttm;

    localtime_s(&ttm, &tt);

    strftime(buffer, 32, "%Y-%m-%d %H:%M:%S", &ttm);

    cout << buffer << endl;

    auto remainder = chrono::duration_cast<chrono::microseconds>(chronoNow.time_since_epoch()) % chrono::seconds(1);

    cout << remainder.count() << endl;

    string timeStr(buffer);

    timeStr += std::format(".{:06d}", remainder.count());

    cout << timeStr << endl;

    // milliseconds since epoch

    auto millisec_since_epoch = chrono::duration_cast<chrono::milliseconds>(chrono::system_clock::now().time_since_epoch());

    cout << millisec_since_epoch << endl;

    cout << millisec_since_epoch.count() << endl;

    cout << millisec_since_epoch / std::chrono::milliseconds(1) << endl;

    // milliseconds since start of the day

    auto now = chrono::system_clock::now();

    auto today = chrono::floor<chrono::days>(now);

    auto hours_since_midninght = duration_cast<hours>(now - today);

    int hours_since_midninght_int = hours_since_midninght.count();

    cout << hours_since_midninght << endl;

    cout << hours_since_midninght_int << endl;

    // chrono in local zone

    auto local_now = chrono::current_zone()->to_local(chrono::system_clock::now());

    auto local_today = chrono::floor<chrono::days>(local_now);

    auto local_hours_elapsed = chrono::duration_cast<chrono::hours>(local_now - local_today);

    cout << local_hours_elapsed << endl;

    cout << local_hours_elapsed.count() << endl;

    return 0;

}
巴特西

cpp chrono basic

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