Subj : Re: lib files
To   : comp.programming
From : puzzlecracker
Date : Sun Oct 09 2005 09:38 am


Scott McPhillips [MVP] wrote:
> puzzlecracker wrote:
> > Can someone provide an explanation for lib files that VS generates - I
> > heard there are static and dynamic ones. How do they differ? what are
> > pros and cons of each?
> >
> >
> > Thanks
> >
>
> A lib (for library) file contains previously compiled code, so you can
> easily include it in your program and call the functions it contains.
>
> In the VS environment this classic definition of a lib file is a
> "static" lib file.  That means it actually contains the code, and when
> you link it in the code becomes part of your exe file.
>
> A "dynamic" lib file is almost empty: It contains only stub functions
> that consist of a jump to someplace else, to be defined at run time.  It
> satisfies the linker's need to put a function address in your exe file,
> but the functions are empty.  The "someplace else" that actually
> contains the functions is a DLL (Dynamic Linking Library) file.  Every
> dynamic lib has a corresponding DLL.  Windows loads the DLL when your
> exe is loaded, and fixes up the jump addresses.
>
> Pros of DLLs: Saves memory if more than one program uses the same
> functions.  Only one copy needs to be loaded into memory.  For example,
> the operating system is largely contained in DLLs shared by all running
> programs.  DLLs also provide a convenient way to divide programming work
> up into separate projects.  Programmer A can build and test his DLL
> without waiting for programmer B to fix some unrelated problem.
>
> Cons of DLLs: Known as "DLL Hell," there can be version management
> problems.  Suppose your program relies on a Microsoft DLL.  Then
> Microsoft updates the DLL in some incompatible way, and some other
> program install brings in the new incompatible DLL file.  Your program dies.
>
> --
> Scott McPhillips [VC++ MVP]


What are prons and cons of static lib and why would you choose them as
opposed to dll?


Another question: when you compile a program that has a main, would lib
be generated or it is only for library types? that is whether exe and
lib are generated together?

.