How to know local drive or not?

If user input filepath+filename, how could we know that is a local drive or not (maybe network drive)?

If user input "\\servername\share-name\filename.exe" then we know the file is on network drive,

but what if he input "H:\filename.exe"?

Can I assume local drive is only C: D: and E: ?

Or is there any function some thing like _IsLocalDrive to verify is a file is on local drive or in network drive?

Thanks