copying files from multiple locations to one destination
 

suppose I have a tree structure like this:
/home/mahmood/sim/a/b/file1.cpp
/home/mahmood/sim/a/b/file2.h
/home/mahmood/sim/a/c/file3.txt
/home/mahmood/sim/d/file4.txt

How can I copy all of them to /home/mahmood/sim. So that when I run "ls" in /home/mahmood/sim, I see all files:
file1.cpp
file2.h
file3.txt
file4.txt

Can 'cp' search for all file and copy them in another folder?

Nope. cp haven't got searching capabilities, it can only use patterns (globbing) that will be expanded by the shell. Anyway you can use find to look for files and apply an action to every file found, e.g.
The echo statement is for testing purposes: the commands will be printed out without being actually executed. Just to review the results before doing the copy. Furthermore you may consider to move or link the files (instead of copying them) to avoid duplicates. Hope this helps.

you can use the command

find /home/mahmood/sim/ -name file* -exec cp {} /home/mahmood/sim/ \;

Thanks it works fine :)