如何将时间四舍五入到最接近的X分钟？

有舍入一个简单的函数UP一DateTime到最近的15分钟？

例如

2011-08-11 16:59 变成 2011-08-11 17:00

2011-08-11 17:00 保持为 2011-08-11 17:00

2011-08-11 17:01 变成 2011-08-11 17:15

DateTime RoundUp(DateTime dt, TimeSpan d)
{
    return new DateTime((dt.Ticks + d.Ticks - 1) / d.Ticks * d.Ticks, dt.Kind);
}

例：

var dt1 = RoundUp(DateTime.Parse("2011-08-11 16:59"), TimeSpan.FromMinutes(15));
// dt1 == {11/08/2011 17:00:00}

var dt2 = RoundUp(DateTime.Parse("2011-08-11 17:00"), TimeSpan.FromMinutes(15));
// dt2 == {11/08/2011 17:00:00}

var dt3 = RoundUp(DateTime.Parse("2011-08-11 17:01"), TimeSpan.FromMinutes(15));
// dt3 == {11/08/2011 17:15:00}

提出了不涉及相乘和除法 的解决方案long。

public static DateTime RoundUp(this DateTime dt, TimeSpan d)
{
    var modTicks = dt.Ticks % d.Ticks;
    var delta = modTicks != 0 ? d.Ticks - modTicks : 0;
    return new DateTime(dt.Ticks + delta, dt.Kind);
}

public static DateTime RoundDown(this DateTime dt, TimeSpan d)
{
    var delta = dt.Ticks % d.Ticks;
    return new DateTime(dt.Ticks - delta, dt.Kind);
}

public static DateTime RoundToNearest(this DateTime dt, TimeSpan d)
{
    var delta = dt.Ticks % d.Ticks;
    bool roundUp = delta > d.Ticks / 2;
    var offset = roundUp ? d.Ticks : 0;

    return new DateTime(dt.Ticks + offset - delta, dt.Kind);
}

用法：

var date = new DateTime(2010, 02, 05, 10, 35, 25, 450); // 2010/02/05 10:35:25
var roundedUp = date.RoundUp(TimeSpan.FromMinutes(15)); // 2010/02/05 10:45:00
var roundedDown = date.RoundDown(TimeSpan.FromMinutes(15)); // 2010/02/05 10:30:00
var roundedToNearest = date.RoundToNearest(TimeSpan.FromMinutes(15)); // 2010/02/05 10:30:00

如果您需要舍入到最近的时间间隔（不向上），那么我建议使用以下方法

    static DateTime RoundToNearestInterval(DateTime dt, TimeSpan d)
    {
        int f=0;
        double m = (double)(dt.Ticks % d.Ticks) / d.Ticks;
        if (m >= 0.5)
            f=1;            
        return new DateTime(((dt.Ticks/ d.Ticks)+f) * d.Ticks);
    }

void Main()
{
    var date1 = new DateTime(2011, 8, 11, 16, 59, 00);
    date1.Round15().Dump();

    var date2 = new DateTime(2011, 8, 11, 17, 00, 02);
    date2.Round15().Dump();

    var date3 = new DateTime(2011, 8, 11, 17, 01, 23);
    date3.Round15().Dump();

    var date4 = new DateTime(2011, 8, 11, 17, 00, 00);
    date4.Round15().Dump();
}

public static class Extentions
{
    public static DateTime Round15(this DateTime value)
    {   
        var ticksIn15Mins = TimeSpan.FromMinutes(15).Ticks;

        return (value.Ticks % ticksIn15Mins == 0) ? value : new DateTime((value.Ticks / ticksIn15Mins + 1) * ticksIn15Mins);
    }
}

结果：

8/11/2011 5:00:00 PM
8/11/2011 5:15:00 PM
8/11/2011 5:15:00 PM
8/11/2011 5:00:00 PM

因为我讨厌重新发明轮子，所以我可能会遵循以下算法将DateTime值四舍五入到指定的时间增量（时间跨度）：

• 将DateTime要舍入的值转换为十进制浮点值，该整数代表单位的整数和小数TimeSpan。
• 使用将其四舍五入为整数Math.Round()。
• 通过将四舍五入的整数乘以TimeSpan单位中的刻度数，可以缩小刻度。
• DateTime从四舍五入的滴答数实例化一个新值，并将其返回给调用方。

这是代码：

public static class DateTimeExtensions
{

    public static DateTime Round( this DateTime value , TimeSpan unit )
    {
        return Round( value , unit , default(MidpointRounding) ) ;
    }

    public static DateTime Round( this DateTime value , TimeSpan unit , MidpointRounding style )
    {
        if ( unit <= TimeSpan.Zero ) throw new ArgumentOutOfRangeException("unit" , "value must be positive") ;

        Decimal  units        = (decimal) value.Ticks / (decimal) unit.Ticks ;
        Decimal  roundedUnits = Math.Round( units , style ) ;
        long     roundedTicks = (long) roundedUnits * unit.Ticks ;
        DateTime instance     = new DateTime( roundedTicks ) ;

        return instance ;
    }

}

我的版本

DateTime newDateTimeObject = oldDateTimeObject.AddMinutes(15 - oldDateTimeObject.Minute % 15);

作为一种方法，它将像这样锁定

public static DateTime GetNextQuarterHour(DateTime oldDateTimeObject)
{
    return oldDateTimeObject.AddMinutes(15 - oldDateTimeObject.Minute % 15);
}

被这样称呼

DateTime thisIsNow = DateTime.Now;
DateTime nextQuarterHour = GetNextQuarterHour(thisIsNow);

优雅？

dt.AddSeconds(900 - (x.Minute * 60 + x.Second) % 900)

注意：上面的公式不正确，即以下内容：

DateTime RoundUp(DateTime dt, TimeSpan d)
{
    return new DateTime(((dt.Ticks + d.Ticks - 1) / d.Ticks) * d.Ticks);
}

应该改写为：

DateTime RoundUp(DateTime dt, TimeSpan d)
{
    return new DateTime(((dt.Ticks + d.Ticks/2) / d.Ticks) * d.Ticks);
}

更详细的解决方案，它使用模并避免不必要的计算。

public static class DateTimeExtensions
{
    public static DateTime RoundUp(this DateTime dt, TimeSpan ts)
    {
        return Round(dt, ts, true);
    }

    public static DateTime RoundDown(this DateTime dt, TimeSpan ts)
    {
        return Round(dt, ts, false);
    }

    private static DateTime Round(DateTime dt, TimeSpan ts, bool up)
    {
        var remainder = dt.Ticks % ts.Ticks;
        if (remainder == 0)
        {
            return dt;
        }

        long delta;
        if (up)
        {
            delta = ts.Ticks - remainder;
        }
        else
        {
            delta = -remainder;
        }

        return dt.AddTicks(delta);
    }
}

这是一个简单的解决方案，可以四舍五入到最接近的1分钟。它保留DateTime的TimeZone和Kind信息。可以对其进行修改以进一步满足自己的需要（如果需要四舍五入到最接近的5分钟等）。

DateTime dbNowExact = DateTime.Now;
DateTime dbNowRound1 = (dbNowExact.Millisecond == 0 ? dbNowExact : dbNowExact.AddMilliseconds(1000 - dbNowExact.Millisecond));
DateTime dbNowRound2 = (dbNowRound1.Second == 0 ? dbNowRound1 : dbNowRound1.AddSeconds(60 - dbNowRound1.Second));
DateTime dbNow = dbNowRound2;

您可以使用此方法，它使用指定的日期来确保它维护先前在datetime对象中指定的任何全球化和datetime类型。

const long LNG_OneMinuteInTicks = 600000000;
/// <summary>
/// Round the datetime to the nearest minute
/// </summary>
/// <param name = "dateTime"></param>
/// <param name = "numberMinutes">The number minute use to round the time to</param>
/// <returns></returns>        
public static DateTime Round(DateTime dateTime, int numberMinutes = 1)
{
    long roundedMinutesInTicks = LNG_OneMinuteInTicks * numberMinutes;
    long remainderTicks = dateTime.Ticks % roundedMinutesInTicks;
    if (remainderTicks < roundedMinutesInTicks / 2)
    {
        // round down
        return dateTime.AddTicks(-remainderTicks);
    }

    // round up
    return dateTime.AddTicks(roundedMinutesInTicks - remainderTicks);
}

.Net小提琴测试

如果要使用“时间跨度”舍入，可以使用它。

/// <summary>
/// Round the datetime
/// </summary>
/// <example>Round(dt, TimeSpan.FromMinutes(5)); => round the time to the nearest 5 minutes.</example>
/// <param name = "dateTime"></param>
/// <param name = "roundBy">The time use to round the time to</param>
/// <returns></returns>        
public static DateTime Round(DateTime dateTime, TimeSpan roundBy)
{            
    long remainderTicks = dateTime.Ticks % roundBy.Ticks;
    if (remainderTicks < roundBy.Ticks / 2)
    {
        // round down
        return dateTime.AddTicks(-remainderTicks);
    }

    // round up
    return dateTime.AddTicks(roundBy.Ticks - remainderTicks);
}

时光小提琴