Difference between comdlg32.ocx and comdlg32.dll

Posted on 2010-03-31
Medium Priority
Last Modified: 2013-11-18
I see both the comdlg32.ocx and the comdlg32.dll in Windows\system32 directory and was wondering what the difference of these files are.  I know the .ocx is ActiveX, but why both files with the same name...do they provide different functions to use.  This is not the only example either,  there is mscomctl.ocx and .dll.  Is there a common approach to these files having both a .ocx and .dll?

Question by:GoPack
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Accepted Solution

John Hurst earned 2000 total points
ID: 29259240
A DLL is a library file, whereas an OCX is an active X control as you noted. An active X control can use a library (which is why you see both). A library is not an active X control, so you need the other. No conflict and no problem - it is the way it was designed. ... Thinkpads_User

Author Comment

ID: 29261051
Thanks Thinkpads_User, so if I understand this right...The .ocx file is like a .exe with a .dll.  The ActiveX control (comdlg32.ocx) calls the dll (comdlg32.dll) just like any other .exe?  And in the ActiveX situation, most likely a .exe calls the comdlg32.ocx which then calls the comdlg32.dll for the function.?

LVL 101

Assisted Solution

by:John Hurst
John Hurst earned 2000 total points
ID: 29265054
I don't think you can be overly strict in this description. An Active X control needs an OCX to run. Something will run the OCX because it is not an EXE all by itself. Now whether an OCX calls a DLL - that would be up to the programmer. However, the way you described above is very likely correct. ... Thinkpads_User
LVL 101

Expert Comment

by:John Hurst
ID: 29277283
Thanks, and I was pleased to assist. ... Thinkpads_User

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