在VB.NET中声明数组的不同方法 [英] Different ways of declaring arrays in VB.NET

问题描述

在VB.NET中，以下声明数组的方式之间有什么区别吗？

In VB.NET, is there any difference between the following ways of declaring arrays?

- Dim cargoWeights(10) as Double

- cargoWeights = New Double(10) {}

'这是两个独立的陈述。

' These are two independent statements. They are not supposed to execute one after the other.

据我所知，第一个只是声明一个数组变量，该变量在某个数组之前保持值为 Nothing。对象分配给它。换句话说，它尚未初始化。

As far as I know, the first one just declares an array variable that holds the value 'Nothing' until some array object is assigned to it. In other words, it is not initialized yet.

但是第二条语句呢？ =符号是否表示该变量已被初始化并且不会包含 Nothing？它会指向11个默认Double值（0.0）的一维数组吗？

But what about the second statement? Does the "=" sign means the variable is already being initialized and won't hold 'Nothing'? Is it going to point to an one-dimensional array of eleven default Double values (0.0)?

编辑：

根据MSDN网站：

下面的示例声明一个数组变量，该变量最初并不指向任何数组。

The following example declares an array variable that does not initially point to any array.

Dim twoDimStrings（，）作为字符串

Dim twoDimStrings( , ) As String

（...）变量twoDimStrings的值为Nothing。

(...) the variable twoDimStrings has the value Nothing.

来源： http://msdn.microsoft.com/zh-cn/library/18e9wyy0（v = vs.80）.aspx

推荐答案

将 Dim cargoWeights（10）都设为Double 和 cargoWeights =新Double（10）{} 实际上将初始化一个double数组，并将每个项目设置为默认类型值，在这种情况下为0.0。 （或者如果 String 数据类型什么也没有）

Both Dim cargoWeights(10) as Double and cargoWeights = New Double(10) {} will actually initialize an array of doubles with each items set to default type value, which in this case, 0.0. (Or Nothing if String data type)

两种语法的区别在于，第二种语法可以将数组中每个项目的值初始化为不同于默认值的值，例如：

The difference between the two syntax is that, the 2nd one you can init the value of each items in the array to different from default value, like:

cargoWeights = New Double(10) {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}

要声明未初始化的数组，请使用 Dim cargoWeights（）为Double 或 cargoWeights = New Double（）{} 。

To declare uninitialized array, use Dim cargoWeights() As Double or cargoWeights = New Double() {}.

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