是否有一种方法可以在。net中表示一个只有时间而没有日期的值?例如，指示商店的开门时间?
TimeSpan表示一个范围，而我只想存储一个时间值。使用DateTime来表示这将导致新的DateTime(1,1,1,8,30,0)，这实际上是不可取的。
当前回答
在c# 10中，你可以使用TimeOnly。
TimeOnly date = TimeOnly.FromDateTime(DateTime.Now);
其他回答
在c# 10中，你可以使用TimeOnly。
TimeOnly date = TimeOnly.FromDateTime(DateTime.Now);
这是一个完整的TimeOfDay类。
对于简单的情况，这有点过分，但如果您像我一样需要更高级的功能，这可能会有所帮助。
它可以处理极端情况、一些基本的数学、比较、与DateTime的交互、解析等。
下面是TimeOfDay类的源代码。你可以在这里看到用法示例并了解更多:
这个类使用DateTime进行大部分内部计算和比较，这样我们就可以利用已经嵌入到DateTime中的所有知识。
// Author: Steve Lautenschlager, CambiaResearch.com
// License: MIT
using System;
using System.Text.RegularExpressions;
namespace Cambia
{
public class TimeOfDay
{
private const int MINUTES_PER_DAY = 60 * 24;
private const int SECONDS_PER_DAY = SECONDS_PER_HOUR * 24;
private const int SECONDS_PER_HOUR = 3600;
private static Regex _TodRegex = new Regex(@"\d?\d:\d\d:\d\d|\d?\d:\d\d");
public TimeOfDay()
{
Init(0, 0, 0);
}
public TimeOfDay(int hour, int minute, int second = 0)
{
Init(hour, minute, second);
}
public TimeOfDay(int hhmmss)
{
Init(hhmmss);
}
public TimeOfDay(DateTime dt)
{
Init(dt);
}
public TimeOfDay(TimeOfDay td)
{
Init(td.Hour, td.Minute, td.Second);
}
public int HHMMSS
{
get
{
return Hour * 10000 + Minute * 100 + Second;
}
}
public int Hour { get; private set; }
public int Minute { get; private set; }
public int Second { get; private set; }
public double TotalDays
{
get
{
return TotalSeconds / (24d * SECONDS_PER_HOUR);
}
}
public double TotalHours
{
get
{
return TotalSeconds / (1d * SECONDS_PER_HOUR);
}
}
public double TotalMinutes
{
get
{
return TotalSeconds / 60d;
}
}
public int TotalSeconds
{
get
{
return Hour * 3600 + Minute * 60 + Second;
}
}
public bool Equals(TimeOfDay other)
{
if (other == null) { return false; }
return TotalSeconds == other.TotalSeconds;
}
public override bool Equals(object obj)
{
if (obj == null) { return false; }
TimeOfDay td = obj as TimeOfDay;
if (td == null) { return false; }
else { return Equals(td); }
}
public override int GetHashCode()
{
return TotalSeconds;
}
public DateTime ToDateTime(DateTime dt)
{
return new DateTime(dt.Year, dt.Month, dt.Day, Hour, Minute, Second);
}
public override string ToString()
{
return ToString("HH:mm:ss");
}
public string ToString(string format)
{
DateTime now = DateTime.Now;
DateTime dt = new DateTime(now.Year, now.Month, now.Day, Hour, Minute, Second);
return dt.ToString(format);
}
public TimeSpan ToTimeSpan()
{
return new TimeSpan(Hour, Minute, Second);
}
public DateTime ToToday()
{
var now = DateTime.Now;
return new DateTime(now.Year, now.Month, now.Day, Hour, Minute, Second);
}
#region -- Static --
public static TimeOfDay Midnight { get { return new TimeOfDay(0, 0, 0); } }
public static TimeOfDay Noon { get { return new TimeOfDay(12, 0, 0); } }
public static TimeOfDay operator -(TimeOfDay t1, TimeOfDay t2)
{
DateTime now = DateTime.Now;
DateTime dt1 = new DateTime(now.Year, now.Month, now.Day, t1.Hour, t1.Minute, t1.Second);
TimeSpan ts = new TimeSpan(t2.Hour, t2.Minute, t2.Second);
DateTime dt2 = dt1 - ts;
return new TimeOfDay(dt2);
}
public static bool operator !=(TimeOfDay t1, TimeOfDay t2)
{
if (ReferenceEquals(t1, t2)) { return true; }
else if (ReferenceEquals(t1, null)) { return true; }
else
{
return t1.TotalSeconds != t2.TotalSeconds;
}
}
public static bool operator !=(TimeOfDay t1, DateTime dt2)
{
if (ReferenceEquals(t1, null)) { return false; }
DateTime dt1 = new DateTime(dt2.Year, dt2.Month, dt2.Day, t1.Hour, t1.Minute, t1.Second);
return dt1 != dt2;
}
public static bool operator !=(DateTime dt1, TimeOfDay t2)
{
if (ReferenceEquals(t2, null)) { return false; }
DateTime dt2 = new DateTime(dt1.Year, dt1.Month, dt1.Day, t2.Hour, t2.Minute, t2.Second);
return dt1 != dt2;
}
public static TimeOfDay operator +(TimeOfDay t1, TimeOfDay t2)
{
DateTime now = DateTime.Now;
DateTime dt1 = new DateTime(now.Year, now.Month, now.Day, t1.Hour, t1.Minute, t1.Second);
TimeSpan ts = new TimeSpan(t2.Hour, t2.Minute, t2.Second);
DateTime dt2 = dt1 + ts;
return new TimeOfDay(dt2);
}
public static bool operator <(TimeOfDay t1, TimeOfDay t2)
{
if (ReferenceEquals(t1, t2)) { return true; }
else if (ReferenceEquals(t1, null)) { return true; }
else
{
return t1.TotalSeconds < t2.TotalSeconds;
}
}
public static bool operator <(TimeOfDay t1, DateTime dt2)
{
if (ReferenceEquals(t1, null)) { return false; }
DateTime dt1 = new DateTime(dt2.Year, dt2.Month, dt2.Day, t1.Hour, t1.Minute, t1.Second);
return dt1 < dt2;
}
public static bool operator <(DateTime dt1, TimeOfDay t2)
{
if (ReferenceEquals(t2, null)) { return false; }
DateTime dt2 = new DateTime(dt1.Year, dt1.Month, dt1.Day, t2.Hour, t2.Minute, t2.Second);
return dt1 < dt2;
}
public static bool operator <=(TimeOfDay t1, TimeOfDay t2)
{
if (ReferenceEquals(t1, t2)) { return true; }
else if (ReferenceEquals(t1, null)) { return true; }
else
{
if (t1 == t2) { return true; }
return t1.TotalSeconds <= t2.TotalSeconds;
}
}
public static bool operator <=(TimeOfDay t1, DateTime dt2)
{
if (ReferenceEquals(t1, null)) { return false; }
DateTime dt1 = new DateTime(dt2.Year, dt2.Month, dt2.Day, t1.Hour, t1.Minute, t1.Second);
return dt1 <= dt2;
}
public static bool operator <=(DateTime dt1, TimeOfDay t2)
{
if (ReferenceEquals(t2, null)) { return false; }
DateTime dt2 = new DateTime(dt1.Year, dt1.Month, dt1.Day, t2.Hour, t2.Minute, t2.Second);
return dt1 <= dt2;
}
public static bool operator ==(TimeOfDay t1, TimeOfDay t2)
{
if (ReferenceEquals(t1, t2)) { return true; }
else if (ReferenceEquals(t1, null)) { return true; }
else { return t1.Equals(t2); }
}
public static bool operator ==(TimeOfDay t1, DateTime dt2)
{
if (ReferenceEquals(t1, null)) { return false; }
DateTime dt1 = new DateTime(dt2.Year, dt2.Month, dt2.Day, t1.Hour, t1.Minute, t1.Second);
return dt1 == dt2;
}
public static bool operator ==(DateTime dt1, TimeOfDay t2)
{
if (ReferenceEquals(t2, null)) { return false; }
DateTime dt2 = new DateTime(dt1.Year, dt1.Month, dt1.Day, t2.Hour, t2.Minute, t2.Second);
return dt1 == dt2;
}
public static bool operator >(TimeOfDay t1, TimeOfDay t2)
{
if (ReferenceEquals(t1, t2)) { return true; }
else if (ReferenceEquals(t1, null)) { return true; }
else
{
return t1.TotalSeconds > t2.TotalSeconds;
}
}
public static bool operator >(TimeOfDay t1, DateTime dt2)
{
if (ReferenceEquals(t1, null)) { return false; }
DateTime dt1 = new DateTime(dt2.Year, dt2.Month, dt2.Day, t1.Hour, t1.Minute, t1.Second);
return dt1 > dt2;
}
public static bool operator >(DateTime dt1, TimeOfDay t2)
{
if (ReferenceEquals(t2, null)) { return false; }
DateTime dt2 = new DateTime(dt1.Year, dt1.Month, dt1.Day, t2.Hour, t2.Minute, t2.Second);
return dt1 > dt2;
}
public static bool operator >=(TimeOfDay t1, TimeOfDay t2)
{
if (ReferenceEquals(t1, t2)) { return true; }
else if (ReferenceEquals(t1, null)) { return true; }
else
{
return t1.TotalSeconds >= t2.TotalSeconds;
}
}
public static bool operator >=(TimeOfDay t1, DateTime dt2)
{
if (ReferenceEquals(t1, null)) { return false; }
DateTime dt1 = new DateTime(dt2.Year, dt2.Month, dt2.Day, t1.Hour, t1.Minute, t1.Second);
return dt1 >= dt2;
}
public static bool operator >=(DateTime dt1, TimeOfDay t2)
{
if (ReferenceEquals(t2, null)) { return false; }
DateTime dt2 = new DateTime(dt1.Year, dt1.Month, dt1.Day, t2.Hour, t2.Minute, t2.Second);
return dt1 >= dt2;
}
/// <summary>
/// Input examples:
/// 14:21:17 (2pm 21min 17sec)
/// 02:15 (2am 15min 0sec)
/// 2:15 (2am 15min 0sec)
/// 2/1/2017 14:21 (2pm 21min 0sec)
/// TimeOfDay=15:13:12 (3pm 13min 12sec)
/// </summary>
public static TimeOfDay Parse(string s)
{
// We will parse any section of the text that matches this
// pattern: dd:dd or dd:dd:dd where the first doublet can
// be one or two digits for the hour. But minute and second
// must be two digits.
Match m = _TodRegex.Match(s);
string text = m.Value;
string[] fields = text.Split(':');
if (fields.Length < 2) { throw new ArgumentException("No valid time of day pattern found in input text"); }
int hour = Convert.ToInt32(fields[0]);
int min = Convert.ToInt32(fields[1]);
int sec = fields.Length > 2 ? Convert.ToInt32(fields[2]) : 0;
return new TimeOfDay(hour, min, sec);
}
#endregion
private void Init(int hour, int minute, int second)
{
if (hour < 0 || hour > 23) { throw new ArgumentException("Invalid hour, must be from 0 to 23."); }
if (minute < 0 || minute > 59) { throw new ArgumentException("Invalid minute, must be from 0 to 59."); }
if (second < 0 || second > 59) { throw new ArgumentException("Invalid second, must be from 0 to 59."); }
Hour = hour;
Minute = minute;
Second = second;
}
private void Init(int hhmmss)
{
int hour = hhmmss / 10000;
int min = (hhmmss - hour * 10000) / 100;
int sec = (hhmmss - hour * 10000 - min * 100);
Init(hour, min, sec);
}
private void Init(DateTime dt)
{
Init(dt.Hour, dt.Minute, dt.Second);
}
}
}
我建议使用DateTime。如果你不需要日期部分，就忽略它。如果你只需要把时间显示给用户，可以这样格式化输出给用户:
DateTime.Now.ToString("t"); // outputs 10:00 PM
似乎所有创建新类或甚至使用TimeSpan的额外工作都是不必要的。
如果您不想使用DateTime或TimeSpan，而只想存储一天中的时间，则可以将午夜以来的秒存储在Int32中，或者(如果您甚至不需要秒)将午夜以来的分钟存储在Int16中。编写从这样的值访问Hour、Minute和Second所需的几个方法是很简单的。
我能想到的避免使用DateTime/TimeSpan的唯一原因是结构的大小很关键。
(当然，如果你使用一个简单的方案，就像上面包装在一个类中，那么它也将是微不足道的存储替换为TimeSpan，如果你突然意识到这将给你一个优势)
您可以简单地使用验证约束。
[DataType(DataType.Time)]
public DateTime OpeningTime { get; set; }
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