我的方法要简单得多。您可以根据需要调整返回字符串

    public static string TimeLeft(DateTime utcDate)
    {
        TimeSpan timeLeft = DateTime.UtcNow - utcDate;
        string timeLeftString = "";
        if (timeLeft.Days > 0)
        {
            timeLeftString += timeLeft.Days == 1 ? timeLeft.Days + " day" : timeLeft.Days + " days";
        }
        else if (timeLeft.Hours > 0)
        {
            timeLeftString += timeLeft.Hours == 1 ? timeLeft.Hours + " hour" : timeLeft.Hours + " hours";
        }
        else
        {
            timeLeftString += timeLeft.Minutes == 1 ? timeLeft.Minutes+" minute" : timeLeft.Minutes + " minutes";
        }
        return timeLeftString;
    }

下面是我作为DateTime类的扩展方法添加的一个实现，它处理未来和过去的日期，并提供了一个近似选项，允许您指定要查找的详细程度（“3小时前”与“3小时、23分钟、12秒前”）：

using System.Text;

/// <summary>
/// Compares a supplied date to the current date and generates a friendly English 
/// comparison ("5 days ago", "5 days from now")
/// </summary>
/// <param name="date">The date to convert</param>
/// <param name="approximate">When off, calculate timespan down to the second.
/// When on, approximate to the largest round unit of time.</param>
/// <returns></returns>
public static string ToRelativeDateString(this DateTime value, bool approximate)
{
    StringBuilder sb = new StringBuilder();

    string suffix = (value > DateTime.Now) ? " from now" : " ago";

    TimeSpan timeSpan = new TimeSpan(Math.Abs(DateTime.Now.Subtract(value).Ticks));

    if (timeSpan.Days > 0)
    {
        sb.AppendFormat("{0} {1}", timeSpan.Days,
          (timeSpan.Days > 1) ? "days" : "day");
        if (approximate) return sb.ToString() + suffix;
    }
    if (timeSpan.Hours > 0)
    {
        sb.AppendFormat("{0}{1} {2}", (sb.Length > 0) ? ", " : string.Empty,
          timeSpan.Hours, (timeSpan.Hours > 1) ? "hours" : "hour");
        if (approximate) return sb.ToString() + suffix;
    }
    if (timeSpan.Minutes > 0)
    {
        sb.AppendFormat("{0}{1} {2}", (sb.Length > 0) ? ", " : string.Empty, 
          timeSpan.Minutes, (timeSpan.Minutes > 1) ? "minutes" : "minute");
        if (approximate) return sb.ToString() + suffix;
    }
    if (timeSpan.Seconds > 0)
    {
        sb.AppendFormat("{0}{1} {2}", (sb.Length > 0) ? ", " : string.Empty, 
          timeSpan.Seconds, (timeSpan.Seconds > 1) ? "seconds" : "second");
        if (approximate) return sb.ToString() + suffix;
    }
    if (sb.Length == 0) return "right now";

    sb.Append(suffix);
    return sb.ToString();
}

public static string ToRelativeDate(DateTime input)
{
    TimeSpan oSpan = DateTime.Now.Subtract(input);
    double TotalMinutes = oSpan.TotalMinutes;
    string Suffix = " ago";

    if (TotalMinutes < 0.0)
    {
        TotalMinutes = Math.Abs(TotalMinutes);
        Suffix = " from now";
    }

    var aValue = new SortedList<double, Func<string>>();
    aValue.Add(0.75, () => "less than a minute");
    aValue.Add(1.5, () => "about a minute");
    aValue.Add(45, () => string.Format("{0} minutes", Math.Round(TotalMinutes)));
    aValue.Add(90, () => "about an hour");
    aValue.Add(1440, () => string.Format("about {0} hours", Math.Round(Math.Abs(oSpan.TotalHours)))); // 60 * 24
    aValue.Add(2880, () => "a day"); // 60 * 48
    aValue.Add(43200, () => string.Format("{0} days", Math.Floor(Math.Abs(oSpan.TotalDays)))); // 60 * 24 * 30
    aValue.Add(86400, () => "about a month"); // 60 * 24 * 60
    aValue.Add(525600, () => string.Format("{0} months", Math.Floor(Math.Abs(oSpan.TotalDays / 30)))); // 60 * 24 * 365 
    aValue.Add(1051200, () => "about a year"); // 60 * 24 * 365 * 2
    aValue.Add(double.MaxValue, () => string.Format("{0} years", Math.Floor(Math.Abs(oSpan.TotalDays / 365))));

    return aValue.First(n => TotalMinutes < n.Key).Value.Invoke() + Suffix;
}

http://refactormycode.com/codes/493-twitter-esque-relative-dates

C#6版本：

static readonly SortedList<double, Func<TimeSpan, string>> offsets = 
   new SortedList<double, Func<TimeSpan, string>>
{
    { 0.75, _ => "less than a minute"},
    { 1.5, _ => "about a minute"},
    { 45, x => $"{x.TotalMinutes:F0} minutes"},
    { 90, x => "about an hour"},
    { 1440, x => $"about {x.TotalHours:F0} hours"},
    { 2880, x => "a day"},
    { 43200, x => $"{x.TotalDays:F0} days"},
    { 86400, x => "about a month"},
    { 525600, x => $"{x.TotalDays / 30:F0} months"},
    { 1051200, x => "about a year"},
    { double.MaxValue, x => $"{x.TotalDays / 365:F0} years"}
};

public static string ToRelativeDate(this DateTime input)
{
    TimeSpan x = DateTime.Now - input;
    string Suffix = x.TotalMinutes > 0 ? " ago" : " from now";
    x = new TimeSpan(Math.Abs(x.Ticks));
    return offsets.First(n => x.TotalMinutes < n.Key).Value(x) + Suffix;
}

使用解构主义和Linq得到“n（最大时间单位）前”的“一行”：

TimeSpan timeSpan = DateTime.Now - new DateTime(1234, 5, 6, 7, 8, 9);

(string unit, int value) = new Dictionary<string, int>
{
    {"year(s)", (int)(timeSpan.TotalDays / 365.25)}, //https://en.wikipedia.org/wiki/Year#Intercalation
    {"month(s)", (int)(timeSpan.TotalDays / 29.53)}, //https://en.wikipedia.org/wiki/Month
    {"day(s)", (int)timeSpan.TotalDays},
    {"hour(s)", (int)timeSpan.TotalHours},
    {"minute(s)", (int)timeSpan.TotalMinutes},
    {"second(s)", (int)timeSpan.TotalSeconds},
    {"millisecond(s)", (int)timeSpan.TotalMilliseconds}
}.First(kvp => kvp.Value > 0);

Console.WriteLine($"{value} {unit} ago");

你在786年前

当前年份和月份，如

TimeSpan timeSpan = DateTime.Now - new DateTime(2020, 12, 6, 7, 8, 9);

您4天前收到

实际日期，比如

TimeSpan timeSpan = DateTime.Now - DateTime.Now.Date;

9小时前到达

我想我应该用类和多态性来尝试一下。我以前的迭代使用了子类，结果开销太大。我已经切换到一个更灵活的委托/公共属性对象模型，这明显更好。我的代码稍微准确一点，我希望我能想出一种更好的方法来生成“几个月前”的代码，而这种方法看起来并没有过度设计。

我想我还是会坚持Jeff的if-then-cascade，因为它的代码更少，而且更简单（肯定更容易确保它按预期工作）。

对于以下代码，PrintRelativeTime.GetRelativeTime message（TimeSpan ago）返回相对时间消息（例如“昨天”）。

public class RelativeTimeRange : IComparable
{
    public TimeSpan UpperBound { get; set; }

    public delegate string RelativeTimeTextDelegate(TimeSpan timeDelta);

    public RelativeTimeTextDelegate MessageCreator { get; set; }

    public int CompareTo(object obj)
    {
        if (!(obj is RelativeTimeRange))
        {
            return 1;
        }
        // note that this sorts in reverse order to the way you'd expect, 
        // this saves having to reverse a list later
        return (obj as RelativeTimeRange).UpperBound.CompareTo(UpperBound);
    }
}

public class PrintRelativeTime
{
    private static List<RelativeTimeRange> timeRanges;

    static PrintRelativeTime()
    {
        timeRanges = new List<RelativeTimeRange>{
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromSeconds(1),
                MessageCreator = (delta) => 
                { return "one second ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromSeconds(60),
                MessageCreator = (delta) => 
                { return delta.Seconds + " seconds ago"; }

            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromMinutes(2),
                MessageCreator = (delta) => 
                { return "one minute ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromMinutes(60),
                MessageCreator = (delta) => 
                { return delta.Minutes + " minutes ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromHours(2),
                MessageCreator = (delta) => 
                { return "one hour ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromHours(24),
                MessageCreator = (delta) => 
                { return delta.Hours + " hours ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.FromDays(2),
                MessageCreator = (delta) => 
                { return "yesterday"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = DateTime.Now.Subtract(DateTime.Now.AddMonths(-1)),
                MessageCreator = (delta) => 
                { return delta.Days + " days ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = DateTime.Now.Subtract(DateTime.Now.AddMonths(-2)),
                MessageCreator = (delta) => 
                { return "one month ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = DateTime.Now.Subtract(DateTime.Now.AddYears(-1)),
                MessageCreator = (delta) => 
                { return (int)Math.Floor(delta.TotalDays / 30) + " months ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = DateTime.Now.Subtract(DateTime.Now.AddYears(-2)),
                MessageCreator = (delta) => 
                { return "one year ago"; }
            }, 
            new RelativeTimeRange
            {
                UpperBound = TimeSpan.MaxValue,
                MessageCreator = (delta) => 
                { return (int)Math.Floor(delta.TotalDays / 365.24D) + " years ago"; }
            }
        };

        timeRanges.Sort();
    }

    public static string GetRelativeTimeMessage(TimeSpan ago)
    {
        RelativeTimeRange postRelativeDateRange = timeRanges[0];

        foreach (var timeRange in timeRanges)
        {
            if (ago.CompareTo(timeRange.UpperBound) <= 0)
            {
                postRelativeDateRange = timeRange;
            }
        }

        return postRelativeDateRange.MessageCreator(ago);
    }
}

public static string RelativeDate(DateTime theDate)
{
    Dictionary<long, string> thresholds = new Dictionary<long, string>();
    int minute = 60;
    int hour = 60 * minute;
    int day = 24 * hour;
    thresholds.Add(60, "{0} seconds ago");
    thresholds.Add(minute * 2, "a minute ago");
    thresholds.Add(45 * minute, "{0} minutes ago");
    thresholds.Add(120 * minute, "an hour ago");
    thresholds.Add(day, "{0} hours ago");
    thresholds.Add(day * 2, "yesterday");
    thresholds.Add(day * 30, "{0} days ago");
    thresholds.Add(day * 365, "{0} months ago");
    thresholds.Add(long.MaxValue, "{0} years ago");
    long since = (DateTime.Now.Ticks - theDate.Ticks) / 10000000;
    foreach (long threshold in thresholds.Keys) 
    {
        if (since < threshold) 
        {
            TimeSpan t = new TimeSpan((DateTime.Now.Ticks - theDate.Ticks));
            return string.Format(thresholds[threshold], (t.Days > 365 ? t.Days / 365 : (t.Days > 0 ? t.Days : (t.Hours > 0 ? t.Hours : (t.Minutes > 0 ? t.Minutes : (t.Seconds > 0 ? t.Seconds : 0))))).ToString());
        }
    }
    return "";
}

我更喜欢这个版本，因为它简洁，并且能够添加新的刻度点。这可以用Timespan的Latest（）扩展来封装，而不是长的1行，但为了发布的简洁，这可以。这修复了一小时前、一小时前的问题，提供了一个小时直到两小时过去