为什么这不能作为IIF功能，而是作为IF声明？ [英] Why won't this work as an IIF function, but will as an IF Statement?

问题描述

以下作品：

If 1=1
    rdoYes.checked = True
Else
    rdoNo.checked = True
End If

但是，以下内容不是工作：

However, the following doesn't work:

IIF(1=1, rdoYes.checked = True, rdoNo.checked = True)

这是为什么？

谢谢！

推荐答案

它确实有效;它只是不能做你想要的。

It does "work"; it just doesn't do what you want.

IIf 在VB.NET中是一个函数（不要使用它，永远，顺便说一下），它采用以下参数：

IIf in VB.NET is a function (don't use it, ever, by the way), which takes these parameters:

1. A Boolean 要检查的条件


2. 如果条件 True 对象 $ c>


3. 如果条件为 False，则返回不同的对象

1. A Boolean condition to check
2. An Object to return if the condition is True
3. A different Object to return if the condition is False

在您的使用中，您的条件是 1 = 1 ;那么你的另外两个参数是 rdoYes.Checked = True 和 rdoNo.Checked = True ，两者都是 VB 来自VB编译器的表达式（所以，实际上，它们等同于更简单的 rdoYes.Checked 和 rdoNo.Checked ）。

In your usage, your condition is 1 = 1; then your two other parameters are rdoYes.Checked = True and rdoNo.Checked = True, both Boolean expressions from the VB compiler's perspective (so, really, they're equivalent to the simpler rdoYes.Checked and rdoNo.Checked).

请记住，在VB.NET中， = 标志仅分配如果它在自己的行。这就是编译器如何区分语句，如 x = 5 和如果x = 5那么。

Remember that in VB.NET, the = sign is only an assignment if it is on its own line. This is how the compiler distinguishes between statements such as x = 5 and If x = 5 Then.

这与您的问题没有直接关系，但您也应该知道 IIf 已被弃用，您几乎应该总是青睐如果而不是：

This is not directly related to your question, but you should also be aware that IIf is deprecated and you should almost always favor If instead:

' Let us just suppose it made sense to write this: '
' Notice the If instead of IIf. '
Dim result = If(1 = 1, rdoYes.Checked, rdoNo.Checked)

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