Статья
11/18/2011

DateTime.MinValue Field

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Represents the smallest possible value of DateTime. This field is read-only.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public Shared ReadOnly MinValue As DateTime

public static readonly DateTime MinValue

Remarks

The value of this constant is equivalent to 00:00:00.0000000, January 1, 0001.

MinValue defines the date and time that is assigned to an uninitialized DateTime variable. The following example illustrates this.

' Define an uninitialized date.
Dim date1 As Date
outputBlock.Text += date1.ToString()
If date1.Equals(Date.MinValue) Then _
   outputBlock.Text += "  (Equals Date.MinValue)" & vbCrLf
' The example displays the following output:
'    1/1/0001 12:00:00 AM  (Equals Date.MinValue)

// Define an uninitialized date.
DateTime date1 = new DateTime();
outputBlock.Text += date1.ToString();
if (date1.Equals(DateTime.MinValue))
   outputBlock.Text += "  (Equals Date.MinValue)" + "\n";
// The example displays the following output:
//    1/1/0001 12:00:00 AM  (Equals Date.MinValue)

The MinValue and MaxValue properties can be used to ensure that a value lies within the supported range before passing it to a DateTime constructor. The code in the Example section illustrates this usage.

Examples

The following example instantiates a DateTime object by passing its constructor an Int64 value that represents a number of ticks. Before invoking the constructor, the example ensures that this value is greater than or equal to DateTime.MinValue.Ticks and less than or equal to DateTime.MinValue.Ticks. If not, it throws an ArgumentOutOfRangeException.

' Attempt to assign an out-of-range value to a DateTime constructor.
Dim numberOfTicks As Long = Int64.MaxValue
Dim validDate As Date

' Validate the value.
If numberOfTicks >= Date.MinValue.Ticks And _
   numberOfTicks <= Date.MaxValue.Ticks Then
   validDate = New Date(numberOfTicks)
ElseIf numberOfTicks < Date.MinValue.Ticks Then
   outputBlock.Text += String.Format("{0:N0} is less than {1:N0} ticks.", _
                                     numberOfTicks, _
                                     Date.MinValue.Ticks)
Else
   outputBlock.Text += String.Format("{0:N0} is greater than {1:N0} ticks.", _
                                     numberOfTicks, _
                                     Date.MaxValue.Ticks)
End If
' The example displays the following output:
'    9,223,372,036,854,775,807 is greater than 3,155,378,975,999,999,999 ticks.

// Attempt to assign an out-of-range value to a DateTime constructor.
long numberOfTicks = Int64.MaxValue;
DateTime validDate;

// Validate the value.
if (numberOfTicks >= DateTime.MinValue.Ticks &&
   numberOfTicks <= DateTime.MaxValue.Ticks)
   validDate = new DateTime(numberOfTicks);
else if (numberOfTicks < DateTime.MinValue.Ticks)
   outputBlock.Text += String.Format("{0:N0} is less than {1:N0} ticks.",
                   numberOfTicks,
                   DateTime.MinValue.Ticks);
else
   outputBlock.Text += String.Format("{0:N0} is greater than {1:N0} ticks.",
                   numberOfTicks,
                   DateTime.MaxValue.Ticks);
// The example displays the following output:
//   9,223,372,036,854,775,807 is greater than 3,155,378,975,999,999,999 ticks.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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