# Using external libraries in Excel VBA



## MrKowz (Dec 22, 2010)

I've seen a lot of code provided on the forums here that uses lines like:


```
Private Declare Function CloseClipboard Lib "user32" () As Long
```
 
or


```
Private Declare Function LockWindowUpdate Lib "user32" (ByVal hwndLock As Long) As Long
```
 
And was wondering where I might be able to find more information on how to use these, what each library has in it, and where in my code these libraries would be helpful.  They seem like they can call in some incredibly powerful functions that will benefit me in the future.

Thanks!


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## RoryA (Dec 22, 2010)

For all things Win API related, start here. 
Also be aware that injudicious use can crash your machine with little to no warning...


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## MrKowz (Dec 22, 2010)

Perfect!  Gives me some "research" to do today at work!


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