VBscsript "SET" question

I know set in VBScript is used for assigning the object reference to the variable. I would like to only understand why its neccessary:

     Set fso = CreateObject("Scripting.FileSystemObject")
what about:
    dim fso
     fso = CreateObject("Scripting.FileSystemObject") //开发者_JAVA百科would not it create the object directly and assign to the variable?

Thanks

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I think its just "because". The language is defined like this. You need it in case of CreateObject and new of a Class.

So its the difference between a normal variable and an object.

The same reason why IsNothing, IsNull, ... exists.

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they are different. If you use Dim to assign a variable, that's just it, a variable. But if you use set , you are actually "initializing" an object reference to a variable so that you can then call the object's "methods" eg.

Set objFS = CreateObject("Scripting.FileSystemObject")

Because now objFS is a reference, you can do things like

Create a folder using objFS.CreateFolder, or delete a folder: objFS.DeleteFolder. Check if a file exists using objFS.FileExists or get a file's extension using objFS.GetExtensionName, among other things.

the concept is much like instantiating a class and using its methods in languages like Java/Python etc.