What is DLL file?

sunnycoder,

>>Dynamic link libraries are stored in files with the DLL file extension.
Usually but not always :) Especially when speaking for Microsoft :)

Venabili,

I realized that ... so lets change it to
Dynamic link libraries are generally stored in files with the DLL file extension.

but DLL extension will be a dynamic link library unless you are working on a crazy system or a crazy person's system ;o)

Sunnycoder

:)

I regularly use ISAPI dll's for creating complex web server applications, I know this isn’t the most common use for them, however you can get an idea of what is within them and how they are used just by browsing a project,

Go to www.davidbirch2.com/cgi-bin/ComicServer.dll/Index/

You can see the file name ComicServer.dll, within that there are various functions in this case separated by //'s each function can have variables passed to it such as this

http://www.davidbirch2.com/cgi-bin/ComicServer.dll/Comic/?comic=1

The function is called Comic and it has a variable named comic passed to it with the value of '1'

Before all the other experts get at me ;) I know most Dll's do not work exactly like this, however they do have the same characteristics, various functions within them and you may pass variables to them as in the above example.... this idea was simply to illustrate the way a Dll file works ;-p)

David

So does all the program have .ddl file, i mean when i intall new program does that program also have .dll file? So to communicate with my machine does this .dll file has to communicate with my OS ddl file?
or ??? please expain me
regards

A Dynamic Link Library is that file which becomes the part of the code at run time.
A program may contain some library function. Normally the declerations of library functions are available at the header file(.h) file, the definition part is available at some other file which is pre-compiled, and ready to link at the run time.

prashant

the question is what many have a doubt about .
in short DLL is a dynamic link library.

If an ActiveX component has been implemented as part of an executable file (EXE file), it is an
out-of-process server and runs in its own process. If it has been implemented as a dynamic link library
(DLL file), it is an in-process server and runs in the same process as the client application.
If your ActiveX component is an out-of-process server, it is an EXE file, and can run standalone.
Applications that use in-process servers usually run faster than those that use out-of-process servers
because the application doesn’t have to cross process boundaries to use an object’s properties, methods,
and events.
There are a few reasons why you may want to create your ActiveX document as an in-process
component (DLL file). The performance of an in-process component surpasses that of the same
component compiled as an EXE. In addition, multiple programs accessing the same EXE can overwrite
global data; that doesn’t happen if they each have their own in-process server.

I find that relying on DLLs can become a pain.  WHen a program has to be installed by multiple users at diverse locations, it seems that the DLL libraries are never the same and maintaining a common set of DLLs across all users becomes impossible. So if possible, I try to compile and build executible modules that do not use the DLLs.