Question

如果我执行以下声明:

dim defaultDate as Date = Nothing

defaultDate 包含 date 结构的默认值

我怀疑有一个干净的方法来重现这个价值, 像某种BUBIN常数, 但我无法找到它。

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Answer 1

如您已经找到的,在 VB.NET 中, nothing 是数值类型的正确方法。

C# 以 default(T) 来“ 明确” 这样做。

Answer 2

价值类型不需要明确初始化。

默认情况下,所有字段初始化为默认值。

dim defaultDate as Date   Nothing not required
Console.WriteLine(defaultDate)   1/1/0001 12:00:00 AM

默认构建器 < a href="" https://stackoverflow.com/a/333840/649524" >这里和

Answer 3

默认 Date 是 Date.Minvalue 。

1月1 001时00分(午夜)

< a href=" "http://msdn.microsoft.com/en-us/library/3eaydw6e%28v=vs.100%29.aspx" rel="nofollow" >Date Data Data Type(视觉基础)

Dim d As Date = Nothing
If d = Date.MinValue Then
      yes, we are really here  
End If

我通常更喜欢Date.minvalue ,而不是 nothing ,但我假定这是品味问题。

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