DateTime.MinValue Field

Definition

表示 DateTime 的最小可能值。Represents the smallest possible value of DateTime. 此字段为只读。This field is read-only.

public: static initonly DateTime MinValue;
public static readonly DateTime MinValue;
 staticval mutable MinValue : DateTime
Public Shared ReadOnly MinValue As DateTime 

Field Value

DateTime

Examples

下面的示例通过将 DateTime 对象的构造函数传递给一个表示刻度数的 Int64 值来实例化该对象。The following example instantiates a DateTime object by passing its constructor an Int64 value that represents a number of ticks. 在调用构造函数之前,该示例确保此值大于或等于 DateTime.MinValue.Ticks 且小于或等于 DateTime.MaxValue.TicksBefore 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.MaxValue.Ticks. 如果不是,则会引发 ArgumentOutOfRangeExceptionIf not, it throws an ArgumentOutOfRangeException.

// 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)
   Console.WriteLine("{0:N0} is less than {1:N0} ticks.",
                     numberOfTicks,
                     DateTime.MinValue.Ticks);
else
   Console.WriteLine("{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.
' 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
   Console.WriteLine("{0:N0} is less than {1:N0} ticks.", 
                     numberOfTicks, 
                     DateTime.MinValue.Ticks)      
Else                                                   
   Console.WriteLine("{0:N0} is greater than {1:N0} ticks.", 
                     numberOfTicks, 
                     DateTime.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.      

Remarks

此常量的值等效于公历的00:00: 00.0000000 UTC,0001年1月1日。The value of this constant is equivalent to 00:00:00.0000000 UTC, January 1, 0001, in the Gregorian calendar.

MinValue 定义分配给未初始化的 DateTime 变量的日期和时间。MinValue defines the date and time that is assigned to an uninitialized DateTime variable. 下面的示例对此进行了演示。The following example illustrates this.

// Define an uninitialized date.
DateTime date1 = new DateTime();
Console.Write(date1);
if (date1.Equals(DateTime.MinValue))
   Console.WriteLine("  (Equals Date.MinValue)");
// The example displays the following output:
//    1/1/0001 12:00:00 AM  (Equals Date.MinValue)
' Define an uninitialized date.
Dim date1 As Date
Console.Write(date1)
If date1.Equals(Date.MinValue) Then _
   Console.WriteLine("  (Equals Date.MinValue)")
' The example displays the following output:
'    1/1/0001 12:00:00 AM  (Equals Date.MinValue)

MinValueMaxValue 属性可用于确保值位于受支持的范围内,然后将其传递到 DateTime 构造函数。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. "示例" 部分中的代码说明了这种用法。The code in the Example section illustrates this usage.

Applies to