如果你有一个长时间的UTC时间戳，还有一个更快的快捷方式。

        /// <summary>
        /// Convert Ticks to Unix Timestamp
        /// </summary>
        /// <param name="time"></param>
        /// <returns></returns>
        public static long ToUnixTimestamp(long time)
        {
            return (time - 621355968000000000) / TimeSpan.TicksPerMillisecond;
        }

使用。net 6.0，使用long避免2038问题:

DateTime。UtcNow到UnixTime:

long seconds = (long)DateTime.UtcNow.Subtract(DateTime.UnixEpoch).TotalSeconds;

(seconds是一个长值，将包含自01/01/1970或UnixTime以来的秒数)

UnixTime到DateTime。UtcNow:

DateTime timestamp = DateTime.UnixEpoch.AddSeconds(seconds);

小提琴:https://dotnetfiddle.net/xNhO6q

截断. totalseconds很重要，因为它被定义为当前系统的值。以整个分数秒表示的timspan结构。

那DateTime的扩展呢?第二种方法可能更令人困惑，在存在属性扩展之前，它是值得的。

/// <summary>
/// Converts a given DateTime into a Unix timestamp
/// </summary>
/// <param name="value">Any DateTime</param>
/// <returns>The given DateTime in Unix timestamp format</returns>
public static int ToUnixTimestamp(this DateTime value)
{
    return (int)Math.Truncate((value.ToUniversalTime().Subtract(new DateTime(1970, 1, 1))).TotalSeconds);
}

/// <summary>
/// Gets a Unix timestamp representing the current moment
/// </summary>
/// <param name="ignored">Parameter ignored</param>
/// <returns>Now expressed as a Unix timestamp</returns>
public static int UnixTimestamp(this DateTime ignored)
{
    return (int)Math.Truncate((DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1))).TotalSeconds);
}

你也可以使用Ticks。我正在为Windows Mobile编写代码，所以没有完整的方法集。我无法使用TotalSeconds。

long epochTicks = new DateTime(1970, 1, 1).Ticks;
long unixTime = ((DateTime.UtcNow.Ticks - epochTicks) / TimeSpan.TicksPerSecond);

or

TimeSpan epochTicks = new TimeSpan(new DateTime(1970, 1, 1).Ticks);
TimeSpan unixTicks = new TimeSpan(DateTime.UtcNow.Ticks) - epochTicks;
double unixTime = unixTicks.TotalSeconds;

下面是一个2-way扩展类，支持:

时区定位 输入/输出以秒或毫秒为单位。

在OP的例子中，用法是:

DateTime.Now.ToUnixtime();

or

DateTime.UtcNow.ToUnixtime();

尽管存在直接的答案，但我认为使用通用方法更好。 特别是因为它很可能是一个需要这样转换的项目，无论如何也需要这些扩展，所以最好对所有人使用相同的工具。

    public static class UnixtimeExtensions
    {
        public static readonly DateTime UNIXTIME_ZERO_POINT = new DateTime(1970, 1, 1, 0, 0,0, DateTimeKind.Utc);

        /// <summary>
        /// Converts a Unix timestamp (UTC timezone by definition) into a DateTime object
        /// </summary>
        /// <param name="value">An input of Unix timestamp in seconds or milliseconds format</param>
        /// <param name="localize">should output be localized or remain in UTC timezone?</param>
        /// <param name="isInMilliseconds">Is input in milliseconds or seconds?</param>
        /// <returns></returns>
        public static DateTime FromUnixtime(this long value, bool localize = false, bool isInMilliseconds = true)
        {
            DateTime result;

            if (isInMilliseconds)
            {
                result = UNIXTIME_ZERO_POINT.AddMilliseconds(value);
            }
            else
            {
                result = UNIXTIME_ZERO_POINT.AddSeconds(value);
            }

            if (localize)
                return result.ToLocalTime();
            else
                return result;
        }

        /// <summary>
        /// Converts a DateTime object into a Unix time stamp
        /// </summary>
        /// <param name="value">any DateTime object as input</param>
        /// <param name="isInMilliseconds">Should output be in milliseconds or seconds?</param>
        /// <returns></returns>
        public static long ToUnixtime(this DateTime value, bool isInMilliseconds = true)
        {
            if (isInMilliseconds)
            {
                return (long)value.ToUniversalTime().Subtract(UNIXTIME_ZERO_POINT).TotalMilliseconds;
            }
            else
            {
                return (long)value.ToUniversalTime().Subtract(UNIXTIME_ZERO_POINT).TotalSeconds;
            }
        }
    }

这是我所使用的:

public long UnixTimeNow()
{
    var timeSpan = (DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0));
    return (long)timeSpan.TotalSeconds;
}

请记住，此方法将返回协调世界时(UTC)的时间。