DateTime.CompareTo 方法

参考

定义

命名空间:: System

程序集:: System.Runtime.dll

程序集:: netstandard.dll

程序集:: mscorlib.dll

重要

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将此实例的值与指定的 DateTime 值相比较，并指示此实例是早于、等于还是晚于指定的 DateTime 值。

重载

CompareTo(DateTime)	将此实例的值与指定的 DateTime 值相比较，并返回一个整数，该整数指示此实例是早于、等于还是晚于指定的 DateTime 值。
CompareTo(Object)	将此实例的值与包含指定的 DateTime 值的指定对象相比较，并返回一个整数，该整数指示此实例是早于、等于还是晚于指定的 DateTime 值。

注解

方法的两个重载返回一个有符号数字，该数字指示此实例的相对值和参数 CompareTo value ，如下表所示。

值	说明
小于零	此实例早于 `value`。
零	此实例与 `value` 相同。
大于零	此实例晚于 `value`。

CompareTo(DateTime)

将此实例的值与指定的 DateTime 值相比较，并返回一个整数，该整数指示此实例是早于、等于还是晚于指定的 DateTime 值。

public:
 virtual int CompareTo(DateTime value);

public int CompareTo (DateTime value);

abstract member CompareTo : DateTime -> int
override this.CompareTo : DateTime -> int

Public Function CompareTo (value As DateTime) As Integer

参数

value: DateTime

要与当前类型进行比较的对象。

Int32

有符号数字，指示此实例和 value 参数的相对值。

值	说明
小于零	此实例早于 `value`。
零	此实例与 `value` 相同。
大于零	此实例晚于 `value`。

实现

CompareTo(T)

示例

以下示例实例化三个对象，一个表示今天的日期，另一个表示一年前的日期，另一个表示将来一 DateTime 年的日期。然后，它 CompareTo(DateTime) 调用方法并显示比较结果。

using System;

public class DateTimeComparison
{
   private enum DateComparisonResult
   {
      Earlier = -1,
      Later = 1,
      TheSame = 0
   };

   public static void Main()
   {
      DateTime thisDate = DateTime.Today;

      // Define two DateTime objects for today's date
      // next year and last year		
      DateTime thisDateNextYear, thisDateLastYear;

      // Call AddYears instance method to add/substract 1 year
      thisDateNextYear = thisDate.AddYears(1);
      thisDateLastYear = thisDate.AddYears(-1);

      // Compare dates
      //
      DateComparisonResult comparison;
      // Compare today to last year
      comparison = (DateComparisonResult) thisDate.CompareTo(thisDateLastYear);
      Console.WriteLine("CompareTo method returns {0}: {1:d} is {2} than {3:d}",
                        (int) comparison, thisDate, comparison.ToString().ToLower(),
                        thisDateLastYear);

      // Compare today to next year
      comparison = (DateComparisonResult) thisDate.CompareTo(thisDateNextYear);
      Console.WriteLine("CompareTo method returns {0}: {1:d} is {2} than {3:d}",
                        (int) comparison, thisDate, comparison.ToString().ToLower(),
                        thisDateNextYear);
   }
}
//
// If run on October 20, 2006, the example produces the following output:
//    CompareTo method returns 1: 10/20/2006 is later than 10/20/2005
//    CompareTo method returns -1: 10/20/2006 is earlier than 10/20/2007

Option Strict On

Module DateTimeComparison
   Private Enum DateComparisonResult
      Earlier = -1
      Later = 1
      TheSame = 0
   End Enum
   
   Public Sub Main()

      Dim thisDate As Date = Date.Today

      ' Define two DateTime objects for today's date 
      ' next year and last year		
      Dim thisDateNextYear, thisDateLastYear As Date

      ' Call AddYears instance method to add/substract 1 year
      thisDateNextYear = thisDate.AddYears(1)
      thisDateLastYear = thisDate.AddYears(-1)   

       
      ' Compare dates
      '
      Dim comparison As DateComparisonResult
      ' Compare today to last year
      comparison = CType(thisDate.CompareTo(thisDateLastYear), DateComparisonResult)
      Console.WriteLine("CompareTo method returns {0}: {1:d} is {2} than {3:d}", _ 
                        CInt(comparison), thisDate, comparison.ToString().ToLower(), _ 
                        thisDateLastYear)
      
      ' Compare today to next year
      comparison = CType(thisDate.CompareTo(thisDateNextYear), DateComparisonResult)
      Console.WriteLine("CompareTo method returns {0}: {1:d} is {2} than {3:d}", _
                        CInt(comparison), thisDate, comparison.ToString().ToLower(), _
                        thisDateNextYear)
   End Sub
End Module
'
' If run on October 20, 2006, the example produces the following output:
'    CompareTo method returns 1: 10/20/2006 is later than 10/20/2005
'    CompareTo method returns -1: 10/20/2006 is earlier than 10/20/2007

注解

若要确定当前实例与的关系，方法将比较当前实例的属性 value CompareTo Ticks value ，但忽略其 Kind 属性。在比较 DateTime 对象之前，请确保对象表示同一时区中的时间。为此，可以比较其 Kind 属性的值。

此方法实现接口，其性能比方法重载略好，因为它不需要将参数 System.IComparable<T> DateTime.CompareTo(Object) 转换为 value 对象。

另请参阅

适用于

CompareTo(Object)

将此实例的值与包含指定的 DateTime 值的指定对象相比较，并返回一个整数，该整数指示此实例是早于、等于还是晚于指定的 DateTime 值。

public:
 virtual int CompareTo(System::Object ^ value);

public:
 int CompareTo(System::Object ^ value);

public int CompareTo (object? value);

public int CompareTo (object value);

abstract member CompareTo : obj -> int
override this.CompareTo : obj -> int

member this.CompareTo : obj -> int

Public Function CompareTo (value As Object) As Integer

参数

value: Object

要比较的装箱对象，或 null。

Int32

一个带符号数字，指示此实例和 value 的相对值。

值	说明
小于零	此实例早于 `value`。
零	此实例与 `value` 相同。
大于零	此实例晚于 `value`，或 `value` 为 `null`。

实现

CompareTo(Object)

例外

ArgumentException

value 不是 DateTime。

示例

下面的示例演示 CompareTo 方法。

using namespace System;
void main()
{
   

   System::DateTime theDay(System::DateTime::Today.Year,7,28);
   int compareValue;
   try
   {
      compareValue = theDay.CompareTo( System::DateTime::Today );
   }
   catch ( ArgumentException^ ) 
   {
      System::Console::WriteLine( "Value is not a DateTime" );
      return;
   }

   if ( compareValue < 0 )
   {
      System::Console::WriteLine( "{0:d} is in the past.", theDay );
   }
   else
   if ( compareValue == 0 )
   {
      System::Console::WriteLine( "{0:d} is today!", theDay );
   }
   else
   // compareValue > 0 
   {
      System::Console::WriteLine( "{0:d} has not come yet.", theDay );
   }
}

System.DateTime theDay = new System.DateTime(System.DateTime.Today.Year, 7, 28);
int compareValue;

try
{
    compareValue = theDay.CompareTo(DateTime.Today);
}
catch (ArgumentException)
{
   Console.WriteLine("Value is not a DateTime");
   return;
}

if (compareValue < 0)
   System.Console.WriteLine("{0:d} is in the past.", theDay);
else if (compareValue == 0)
   System.Console.WriteLine("{0:d} is today!", theDay);
else // compareValue > 0
   System.Console.WriteLine("{0:d} has not come yet.", theDay);

Dim thDay As New System.DateTime(System.DateTime.Today.Year, 7, 28)

Dim compareValue As Integer
Try
   compareValue = thDay.CompareTo(System.DateTime.Today)
Catch exp As ArgumentException
   System.Console.WriteLine("Value is not a DateTime")
End Try

If compareValue < 0 Then
   System.Console.WriteLine("{0:d} is in the past.", thDay)
ElseIf compareValue = 0 Then
   System.Console.WriteLine("{0:d} is today!", thDay)
Else   ' compareValue >= 1 
   System.Console.WriteLine("{0:d} has not come yet.", thDay)
End If

注解

的任何实例 DateTime （无论其值如何）都被视为大于 null 。

另请参阅

适用于

DateTime.CompareTo 方法

定义

重载

注解

CompareTo(DateTime)

参数

返回

实现

示例

注解

另请参阅

适用于

CompareTo(Object)

参数

返回

实现

例外

示例

注解

另请参阅

适用于

其他资源