I never understood the logic or lack of it in postings like these...You asked questions like - "My question is Y DLL?" and have statements like "can not b achieved" and "blah blah blah......" and you expect a coherent reply with details.

ok. what about this one?

y we use DLL files? i know it has advantages and benefits if we use DLL files because several applications will b using the same file and will save memory. But is there any problem which can only b solved only with DLL files. and has no other solution.

Precisely i want to ask where we should use DLL files and where not.

>> Y we use DLL files?

Answer: Y not?

>>where we should use DLL files and where not
DLLs are never actually required -- the same thing could be accomplished by using statically-linked libraries. But then that would make the operating system and all the programs on it very very huge. You might not have a large enough disk drive to hold all that duplicate code.

One case is internationalizing programs. Instead of writing a whole program for each language (e.g. Entlish, Spanish, German, Chinese, etc) it can be done by writing language-specific resource DLLs. One program, many language-specific DLLs.