C# 时间计算的问题

Question

开始时间减结束时间，建议看看TimeSpan

Answer 1

    //dt表示开始的时间
    public int SubDateTime(DateTime dt)
    {
        TimeSpan ts = DateTime.Now.Subtract(dt);
        return ts.Seconds; //秒，还可ts.Milliseconds;微秒 ts.Minutes;分等等;
    }

Answer 2

public static string DateDiff(DateTime _dateTime)
    {
        string ReturnStr = "";
        DateTime dt1 = Convert.ToDateTime(_dateTime);
        DateTime dt2 = Convert.ToDateTime(DateTime.Now);
        TimeSpan ts = dt2 - dt1;
        if (ts.TotalSeconds < 60)
        {
            ReturnStr = ((int)(ts.TotalSeconds)).ToString() + "秒前";
        }
        else
        {
            if (ts.TotalMinutes < 60)
            {
                ReturnStr = ((int)(ts.TotalMinutes)).ToString() + "分钟前";
            }
            else
            {
                if (ts.TotalHours < 24)
                {
                    ReturnStr = ((int)(ts.TotalHours)).ToString() + "小时前";
                }
                else
                {
                    ReturnStr = _dateTime.ToShortDateString();
                }
            }
        }
        return ReturnStr;
    }