在 VBScript 中，如何检索 InstancesOf 集合的第一个元素？

Question

我正在编写一个 VBScript 来识别 OS 细节。我在这里使用 InstancesOf Win32_Operating 系统找到了一个示例，但我不想使用示例中的 foreach 循环，而是只想解决第一次出现的问题，所以我做了：

Set SystemSet = GetObject("winmgmts:").InstancesOf ("Win32_OperatingSystem")
Set System = SystemSet.Item(0)

也尝试过 Set System = SystemSet(0)，但每次我都会收到一般性失败错误消息（法语为 Echec générique）。

我怎样才能做到这一点，然后我才能比较 System.Caption 字符串？

Answer 1

GetObject("winmgmts:")returns一个SWbemServices对象。根据 SWbemServices 对象的文档 InstanceOf() 方法：

^{From SWbemServices.InstancesOf method}
creates an enumerator that returns the instances of a specified class according to the user-specified selection criteria.

枚举器的想法是枚举一组对象，这有助于 VBScript For Each statement 迭代枚举器。

一个简单的例子是；

Dim swbemInstances, swbemInstance
Set swbemInstances = GetObject("winmgmts:").InstancesOf("Win32_OperatingSystem")
For Each swbemInstance In swbemInstances
  WScript.Echo swbemInstance.Caption
Next

您可以使用 ItemIndex 方法直接从枚举器访问实例，如文档所述；

^{From SWbemObjectSet.ItemIndex method}
returns the SWbemObject associated with the specified index into the collection. The index indicates the position of the element within the collection. Collection numbering starts at zero.

Note: Interesting point the documentation actually cites the Win32_OperatingSystem class as an example where you likely want to retrieve only one instance and explains how to use ItemIndex to facilitate it.

^{From SWbemObjectSet.ItemIndex method - Examples}
Only one instance of Win32_OperatingSystem exists for each operating system installation. Creating the GetObject path to obtain the single instance is awkward so scripts normally enumerate Win32_OperatingSystem even though only one instance is available. The following VBScript code example shows how to use the ItemIndex method to get to the one Win32_OperatingSystem without using a For Each loop.

有点像；

Dim swbemInstance
Set swbemInstance = GetObject("winmgmts:").InstancesOf("Win32_OperatingSystem").ItemIndex(0)
WScript.Echo swbemInstance.Caption

中也提到

在 VBScript 中，如何检索 InstancesOf 集合的第一个元素？

In VBScript, how can I retrieve the first element of an InstancesOf collection?

vbscript

wmi