View Full Version : What are dll's

Poppa John
02-07-2002, 03:44 AM
Have seen references to "dll's" now & again in F1. What are they? Are they goodies or baddies? Curious Poppa John ?:|

Ps Have just made a half century in Posts P J:^O

Poppa John
02-07-2002, 03:50 AM
I think I talk too much !!!!! Garrulous Poppa John :8}

02-07-2002, 09:21 AM
dll files are "dynamic link libraries" or specific "routines" that programs can call up, to save rewriting the code thousands of times for many programs. These libraries are written once and can be used by many programs.
They are not programs in their own right, just segments of code that are called up.
If you search on google there will be god information.

Poppa John
03-07-2002, 10:41 AM
Not really any the wiser But will pretend I am ?:| Thick Poppa John

03-07-2002, 10:51 AM
Consider this analogy....
When you ese Internet Explorer, it needs to access your modem to see if any information has arrived:

The programmers could write the code inside Internet Explorer to do this.

When you use Outlook Express to check e-mails, Outlook Express needs to check your modem to see if any information has arrived....

When you use windows update, it needs to check your madem to see if any information has arrived....

Now, they could all write essentially identical code within each program, or they could write code once only and put it in a library file that all other programs could use. a "dll".

Repeat the above for moving the mouse, detecting keystrokes, moving the cursor, or any other common tasks that multiple programs need to perform.

Now Poppa John, a question for you.

Do you keep a separate phone book for each number you look up? Or do you use one phone book for all numbers. Think of it as a "dll"

Graham L
03-07-2002, 04:00 PM
Another term for this is "shared library". A DLL is a package of calllable functions. Windows provides a huge number of these --- so that toolbars, buttons, access to files on disks, control of standard devices such as keyboards, mice, monitors can be used by programmes without the programmer writing his own code and "reinventing the triangular wheel". Look at the size of some ".exe" programmes. Think how big they would be if they had the Windows code included too.
It's also a way of ensuring that all programmes using a particular function have the same bugs. ]:)

Poppa John
03-07-2002, 04:40 PM
Ok I see it now, thanks Poppa John :)

Dolby Digital
03-07-2002, 06:11 PM
dll's are a Windows thing. Other operating systems implement shared code in other ways but the concept is similar. It all works well when the versions are in step, chaos can ensue when things get out of step e.g. a new version of a dll is loaded onto your system when you install a new program but an already installed program may take a dislike to the new version of the dll.

03-07-2002, 06:12 PM
That is called "DLL HELL"

Terry Porritt
03-07-2002, 06:19 PM
Now that you have idea of what dlls' are, here is another problem with them. They come in different version numbers, and when programs are installed, existing newer versions are sometimes overwritten with older ones. This can then cause real problems running programs that require the newer ones.

System File Checker is a useful tool to help sort this out.

Other problems can arise when a program puts a dll into its own program folder, and there is another version in the System folder.
If then you try to run 2 programs at once each requiring the same dll but being called from different places a crash will occur because you cant have 2 instances of the same named dll running at the same time.

Gets complicated, doesnt it?

Graham L
03-07-2002, 06:24 PM
No, it's called Windows. ]:)

Terry Porritt
03-07-2002, 06:39 PM
Fazakerly, now what else can we blame Microsoft for?

Poppa John
03-07-2002, 07:21 PM
Hells Teeth, I think I will go back to Chalk & Slate like I used to learn to write on in Wales a 100yrs ago, (it feels like a hundred in this cold wet weather. Old-fashioned Poppa John :^O :^O

dum dugie
03-07-2002, 07:51 PM
cripes--dynamic link libraries eh?
and I thought peoples just couldn't spell...............