[C#] Date类型

很多人提出C#需要有个单独的Date类型，以便干净的处理日期。

微软的人声称Datetime类型是Date类型的超集，所以没有必要单独的Date类型。但很多人明显并不认可这个答案。

下面是我提供的一个Date class实现，给需要的同学：

using System;using System.Globalization;using System.Runtime.Serialization;namespace System{/// <summary>/// 专门用来处理日期的class，不会有‘时分秒’的干扰/// </summary>public struct Date : IComparable, IFormattable, ISerializable, IComparable<Date>, IEquatable<Date>{private DateTime _dt;//这个变量的时分秒都应该始终是0public static readonly Date MaxValue = new Date(DateTime.MaxValue);public static readonly Date MinValue = new Date(DateTime.MinValue);public Date(int year, int month, int day){this._dt = new DateTime(year, month, day);}public Date(DateTime dateTime){this._dt = dateTime.AddTicks(-dateTime.Ticks % TimeSpan.TicksPerDay);}public static TimeSpan operator -(Date d1, Date d2){return d1._dt - d2._dt;}public static Date operator -(Date d, TimeSpan t){return new Date(d._dt - t);}public static bool operator !=(Date d1, Date d2){return d1._dt != d2._dt;}public static Date operator +(Date d, TimeSpan t){return new Date(d._dt + t);}public static bool operator <(Date d1, Date d2){return d1._dt < d2._dt;}public static bool operator <=(Date d1, Date d2){return d1._dt <= d2._dt;}public static bool operator ==(Date d1, Date d2){return d1._dt == d2._dt;}public static bool operator >(Date d1, Date d2){return d1._dt > d2._dt;}public static bool operator >=(Date d1, Date d2){return d1._dt >= d2._dt;}public static implicit operator DateTime(Date d){return d._dt;}public static explicit operator Date(DateTime d){return new Date(d);}public int Day{get{return this._dt.Day;}}public DayOfWeek DayOfWeek{get{return this._dt.DayOfWeek;}}public int DayOfYear{get{return this._dt.DayOfYear;}}public int Month{get{return this._dt.Month;}}public static Date Today{get{return new Date(DateTime.Today);}}public int Year{get{return this._dt.Year;}}/// <summary>/// 返回上一天/// </summary>public Date Yesterday{get{return this.AddDays(-1);}}/// <summary>/// 返回下一天/// </summary>public Date Tomorrow{get{return this.AddDays(1);}}public Date AddDays(int value){return new Date(this._dt.AddDays(value));}public Date AddMonths(int value){return new Date(this._dt.AddMonths(value));}public Date AddYears(int value){return new Date(this._dt.AddYears(value));}public static int Compare(Date d1, Date d2){return d1.CompareTo(d2);}public int CompareTo(Date value){return this._dt.CompareTo(value._dt);}public int CompareTo(object value){return this._dt.CompareTo(value);}public static int DaysInMonth(int year, int month){return DateTime.DaysInMonth(year, month);}public bool Equals(Date value){return this._dt.Equals(value._dt);}public override bool Equals(object value){return value is Date && this._dt.Equals(((Date)value)._dt);}public override int GetHashCode(){return this._dt.GetHashCode();}public static bool Equals(Date d1, Date d2){return d1._dt.Equals(d2._dt);}void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context){info.AddValue("ticks", this._dt.Ticks);}public static bool IsLeapYear(int year){return DateTime.IsLeapYear(year);}public static Date Parse(string s){return new Date(DateTime.Parse(s));}public static Date Parse(string s, IFormatProvider provider){return new Date(DateTime.Parse(s, provider));}public static Date Parse(string s, IFormatProvider provider, DateTimeStyles style){return new Date(DateTime.Parse(s, provider, style));}public static Date ParseExact(string s, string format, IFormatProvider provider){return new Date(DateTime.ParseExact(s, format, provider));}public static Date ParseExact(string s, string format, IFormatProvider provider, DateTimeStyles style){return new Date(DateTime.ParseExact(s, format, provider, style));}public static Date ParseExact(string s, string[] formats, IFormatProvider provider, DateTimeStyles style){return new Date(DateTime.ParseExact(s, formats, provider, style));}public TimeSpan Subtract(Date value){return this - value;}public Date Subtract(TimeSpan value){return this - value;}/// <summary>/// "Thursday, July 4, 2013"/// </summary>/// <returns></returns>public string ToLongString(){return this._dt.ToLongDateString();}/// <summary>/// "7/4/2013"/// </summary>/// <returns></returns>public string ToShortString(){return this._dt.ToShortDateString();}/// <summary>/// "7/4/2013"/// </summary>/// <returns></returns>public override string ToString(){return this.ToShortString();}public string ToString(IFormatProvider provider){return this._dt.ToString(provider);}/// <summary>/// format="s"可以返回"2013-07-04"格式/// </summary>/// <param name="format"></param>/// <returns></returns>public string ToString(string format){if (format == "O" || format == "o" || format == "s"){return this.ToString("yyyy-MM-dd");}return this._dt.ToString(format);}public string ToString(string format, IFormatProvider provider){return this._dt.ToString(format, provider);}/// <summary>/// 获取形如20150702这样格式的日期/// </summary>/// <returns></returns>public int ToInt(){int ret = _dt.Year * 10000 + _dt.Month * 100 + _dt.Day;return ret;}/// <summary>/// 获取形如20150702这样格式的日期/// </summary>/// <returns></returns>public string ToIntString(){return ToInt().ToString();}public static bool TryParse(string s, out Date result){DateTime d;bool success = DateTime.TryParse(s, out d);result = new Date(d);return success;}public static bool TryParse(string s, IFormatProvider provider, DateTimeStyles style, out Date result){DateTime d;bool success = DateTime.TryParse(s, provider, style, out d);result = new Date(d);return success;}public static bool TryParseExact(string s, string format, IFormatProvider provider, DateTimeStyles style, out Date result){DateTime d;bool success = DateTime.TryParseExact(s, format, provider, style, out d);result = new Date(d);return success;}public static bool TryParseExact(string s, string[] formats, IFormatProvider provider, DateTimeStyles style, out Date result){DateTime d;bool success = DateTime.TryParseExact(s, formats, provider, style, out d);result = new Date(d);return success;}}public static class DateTimeExtensions{public static Date ToDate(this DateTime dt){return new Date(dt);}}}

同样的代码也在GitHub上有： https://github.com/wsq003/DateClass