C++时间处理3-格式化时间戳

#include <string>
#include <cstdint>

/**
 * @brief Time unit enum.
 *
 */
enum class timeunit
{
    /** second */
    s,
    /** millisecond */
    ms,
    /** microsecond */
    us,
};

/**
 * @brief Format a timestamp to a human-readable string with a given format.
 *
 * @param second the timestamp in seconds.
 * @param local whether to use local time or UTC time, default is local time.
 * If local is true, the function will format the timestamp to local time, otherwise, it will format the timestamp to UTC time.
 * @param fmt the format of the formatted string. useage like std::put_time, see https://en.cppreference.com/w/cpp/io/manip/put_time
 * @return std::string the formatted string.
 */
std::string fmt_timestamp(uint64_t second, bool local, const std::string &fmt);
/**
 * @brief Format a timestamp to a human-readable string.
 *
 * @param second the timestamp in seconds.
 * @param local whether to use local time or UTC time, default is local time.
 * If local is true, the function will format the timestamp to local time, otherwise, it will format the timestamp to UTC time.
 * @return std::string the formatted string.
 */
std::string fmt_timestamp_s(uint64_t second, bool local = true);
/**
 * @brief Format a timestamp to a human-readable string.
 *
 * @param ms the timestamp in milliseconds.
 * @param local whether to use local time or UTC time, default is local time.
 * If local is true, the function will format the timestamp to local time, otherwise, it will format the timestamp to UTC time.
 * @return std::string the formatted string.
 */
std::string fmt_timestamp_ms(uint64_t ms, bool local = true);
/**
 * @brief Format a timestamp to a human-readable string.
 *
 * @param us the timestamp in microseconds.
 * @param local whether to use local time or UTC time, default is local time.
 * If local is true, the function will format the timestamp to local time, otherwise, it will format the timestamp to UTC time.
 * @return std::string the formatted string.
 */
std::string fmt_timestamp_us(uint64_t us, bool local = true);

#include "timeutil.h"
#include <iomanip>

constexpr static int THOUSAND = 1000;
constexpr static int MILLION = 1000000;

// https://blog.csdn.net/u010087712/article/details/50731222
std::string fmt_timestamp(uint64_t second, bool local, const std::string &fmt)
{
    std::time_t t(second);
    struct tm datetime;
    if (local)
    {
        datetime = localtime_security(t);
    }
    else
    {
        datetime = gmtime_security(t);
    }

    std::stringstream ss;
    ss << std::put_time(&datetime, fmt.c_str());
    return ss.str();
}

// 格式化时间戳，second单位：秒
std::string fmt_timestamp_by_unit(uint64_t t, timeunit unit, bool local)
{
    uint64_t s = 0;
    std::string extension;
    switch (unit)
    {
    case timeunit::s:
        s = t;
        break;
    case timeunit::ms:
    {
        s = t / THOUSAND;
        auto ms = t % THOUSAND;
        extension += "." + fmt_uint(ms, 3);
    }
    break;
    case timeunit::us:
    {
        s = t / MILLION;
        auto us = t % MILLION;
        extension += "." + fmt_uint(us, 6);
    }
    break;
    default:
        break;
    }

    std::string fmt("%Y-%m-%d %H:%M:%S");
    auto time_str = fmt_timestamp(s, local, fmt);
    time_str += extension;
    return time_str;
}

std::string fmt_timestamp_s(uint64_t t, bool local)
{
    return fmt_timestamp_by_unit(t, timeunit::s, local);
}

std::string fmt_timestamp_ms(uint64_t t, bool local)
{
    return fmt_timestamp_by_unit(t, timeunit::ms, local);
}

std::string fmt_timestamp_us(uint64_t t, bool local)
{
    return fmt_timestamp_by_unit(t, timeunit::us, local);
}

#include "timeutil.h"
#include "common.hpp"

void TestFormatTime()
{
    PrintSubTitle("TestFormatTime");
    // timestamp
    auto curTimeS = cutl::timestamp(cutl::timeunit::s);
    auto curTimeMS = cutl::timestamp(cutl::timeunit::ms);
    auto curTimeUS = cutl::timestamp(cutl::timeunit::us);
    std::cout << "current datetime s: " << cutl::fmt_timestamp_s(curTimeS) << std::endl;
    std::cout << "current datetime s in UTC: " << cutl::fmt_timestamp(curTimeS, false, "%Y/%m/%d %H:%M:%S") << std::endl;
    std::cout << "current datetime ms: " << cutl::fmt_timestamp_ms(curTimeMS) << std::endl;
    std::cout << "current datetime ms in UTC: " << cutl::fmt_timestamp_ms(curTimeMS, false) << std::endl;
    std::cout << "current datetime us: " << cutl::fmt_timestamp_us(curTimeUS) << std::endl;
}