DLL's explained?

[Macdave_19]

Hi everyone,

Im trying to read up on DLL's and how to call upon them etc etc. i was wondering if there were some simple DLL's that i could call up to practice a little and what each one actually show's I.E "advapi32.dll" can be used to obtain the username of the person logged onto the computer.

any others that may offer simple info etc?

any help is much appreciated!!

[Leith Ross]

Hello Macdave_19,

While understanding the structure of a DLL (Data Link Library) is helpful, you will need more detailed information on the API calls the DLL contains. API calls don't have intellisense like VBA to show you what the argument name and type are. Incorrectly calling an API function can easily crash the computer.

It helps to have an understanding of "C", since most DLL are written in "C". You need to understand "C" variable types and their VB counterparts, or the function will fail. Since DLL are executable files (compiled), you really can't view the contents.

The basic format for call a DLL is...
Private, Public - default is Public
Declare - Tells VB this a DLL Function or Sub
Function, Sub - 99% of DLL return values. If a value is returned use Function, otherwise Sub.
<DLL name> - Names are case sensitive (string)
Lib - The DLL library name (string)
[Alias] - The DLL name. Use this option when the name conflicts with a VB keyword, or you want the name to be more understandable. This allows you to use a different name after the Function or Sub.
<name As type> - Arguments are enclosed in parentheses and separated by commas. Arguments can be called ByRef or ByVal, if omitted the default is ByRef

Here are 2 Simple API calls to help illustrate their use. To use these be located in a Standard VBA Module, and made Public if they are to be called from outside the module they are in.

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Sincerely,
Leith Ross

[Macdave_19]

Cheers for the help Leith it's much appreciated, maybe i should look into starting "C"!!

Cheers once again!!