C# 可为空的日期时间？
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Nullable DateTime?
提问by hazem
how to create setter and getter Properties for nullable datetime. for example:
如何为可为空的日期时间创建 setter 和 getter 属性。例如：
private DateTime mTimeStamp;
public DateTime TimeStamp
{
get { return mTimeStamp; }
set { mTimeStamp = value; }
}
Does nullable attributes support setter and getter or have i to declare it public?
可空属性是否支持 setter 和 getter 或让 i 将其声明为 public？
private DateTime? mTimeStamp;
public DateTime TimeStamp
{
}
采纳答案by Yuck
You can just do this instead:
你可以这样做：
public DateTime? TimeStamp { get; set; }
If you were having trouble with the compiler it's probably because you only changed one of the associated parts - either the privatemember variable or the property's data type. They need to match, of course, and auto-properties handles that for you nicely.
如果您在编译器方面遇到问题，那可能是因为您只更改了相关部分之一——private成员变量或属性的数据类型。当然，它们需要匹配，并且自动属性可以很好地为您处理。
EDITJust to further clarify, DateTime?is not merely decorated with an ?attribute - it's entirelydifferent from DateTime. DateTime?is shorthand for Nullable<DateTime>, which is a generic (Nullable<T>) that provides nullable support to non-reference types by wrapping the generic parameter T, which is a struct.
编辑只是为了进一步澄清，DateTime?不只是装饰用?属性-它是完全不同DateTime。DateTime?是 的简写Nullable<DateTime>，它是一个泛型 ( Nullable<T>)，它通过包装泛型参数为非引用类型提供可为空的支持，泛型参数T是struct.
回答by Abe Miessler
You should be able to make a DateTime nullable in this way:
您应该能够以这种方式使 DateTime 可以为空：
private DateTime? mTimeStamp;
public DateTime? TimeStamp
{
get { return mTimeStamp; }
set { mTimeStamp = value; }
}
You can use this modifier on other types as well. Read up here: http://msdn.microsoft.com/en-us/library/1t3y8s4s%28v=VS.100%29.aspx
您也可以在其他类型上使用此修饰符。在这里阅读：http: //msdn.microsoft.com/en-us/library/1t3y8s4s%28v=VS.100%29.aspx
回答by John Kalberer
You can create the property in the same way as a normal DateTimeproperty:
您可以以与普通DateTime属性相同的方式创建属性：
public DateTime? TimeStamp { get; set; }
回答by Kirk Woll
A nullable DateTime is a discrete type from a regular DateTime and can be used like any other type. So your code would be:
可为空的 DateTime 是常规 DateTime 的离散类型，可以像任何其他类型一样使用。所以你的代码是：
private DateTime? mTimeStamp;
public DateTime? TimeStamp
{
get { return mTimeStamp; }
set { mTimeStamp = value; }
}
回答by Cymen
It's the same as non-nullable:
它与不可为空相同：
public DateTime? TimeStamp { get; set; }
public DateTime? TimeStamp { get; set; }
You can replace DateTimewith DateTime?in your top sample code (looks like code is missing at the bottom of your post).
您可以替换DateTime与DateTime?在顶部的示例代码（貌似代码在您的文章底部缺失）。
回答by Jason Meckley
private DateTime? mTimeStamp;
public DateTime? TimeStamp
{
get { return mTimeStamp; }
set { mTimeStamp = value; }
}
or, if you are using .net 3.0+
或者，如果您使用的是 .net 3.0+
public DateTime? TimeStamp {get;set;}
