VB.NET 空合并运算符？
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VB.NET null coalescing operator?
提问by RiddlerDev
Possible Duplicates:
Coalesce operator and Conditional operator in VB.NET
Is there a VB.NET equivalent for C#'s ?? operator?
Is there a built-in VB.NET equivalent to the C# null coalescing operator?
是否有与 C# 空合并运算符等效的内置 VB.NET？
回答by Cody Gray
Yes, there is, a long as you're using VB 9 or later (included with Visual Studio 2008).
是的，只要您使用的是 VB 9 或更高版本（包含在 Visual Studio 2008 中）。
You can use the version of the Ifoperatoroverloaded to accept only two arguments:
您可以使用重载的If运算符版本来仅接受两个参数：
Dim myVar? As Integer = Nothing
Console.WriteLine(If(myVar, 7))
More information can be found herein a blog post by the VB.NET team.
更多信息可以发现这里在用VB.NET团队博客文章。
(Yes, this is an operator, even though it looks like a function. It will compile down to the same IL as the "proper" null-coalescing operator in C#.)
（是的，这是一个operator，即使它看起来像一个函数。它会编译成与 C# 中“正确的”空合并运算符相同的 IL。）
Example
例子
Dim b As Boolean?
Console.WriteLine("{0}.", If(b, "this is expected when b is nothing"))
'output: this is expected when b is nothing.
b = False
Console.WriteLine("{0}.", If(b, "this is unexpected when b is false"))
'output: False.
b = True
Console.WriteLine("{0}.", If(b, "this is unexpected when b is true"))
'output: True.
回答by davecoulter
I don't believe that there is a built in VB.Net equivalent, but here's an answer: null coalesce operator in VB.Net(8)
我不相信有内置的 VB.Net 等效项，但这里有一个答案：VB.Net(8) 中的 null 合并运算符
回答by user541686
No. Use GetValueOrDefault; that's why it's there!
号 使用GetValueOrDefault; 这就是为什么它在那里！
