How to get the path of a dll from registry

Hi,
How to retrieve the path of a dll from registry from my C++ code.I explain the problem--
When we register any dll it stores in registry under some key(may be root key like HKEY_CLASS_ROOT or HKEY_LOCAL_MACHINE).Through registry editor we can find this dll by simply providing the name of dll like Test.dll in Find submenu and it gives the location of the dll under different keys.The default value name provides the complete path of dll(system path) thus we can know the path of dll.It is very simple through registry editor.Now i want the same task to be done through my C++ code,i will give the name of Dll for ex Test.dll(remember i don't have any other information about the dll like progid,clsid) and my program searches the registry and will retrieve the path of the dll.I am fairly confident that this is possible because registry editor does this internally.
Please reply fast,it is very urgent.
Thanks.