Sooner or later, every programmer wants  to access drive and folder information.  I've had many questions about the techniques, so I  decided to post this demo program.  

 FindFirst and FindNext  functions are used to access folder information .  Windows API functions   GetLogicalDriveStrings and GetDriveType  give us access to drive information.    Their usage is straightforward once you know which functions to use.  

The program will 

• List drive letters for specified drive types (I chose to make Fixed, Network and CD-Rom types selectable),
• List a random file name from all files on all drives of selected types, and
• List the first 100  file names  matching a given file mask.    If you have Delphi version above Standard, you have access to a   MatchesMask function in the Masks unit which  provides a real mask matching test.   It ,might seem that  FindFirst masking would be useful but  recursive  searching of subdirectories makes its use problematic. (We have to search with mask of *,* to ensure that all folders are retuned).   MatchesMask is a cleaner solution.   If you have Delphi Standard, there is commented code to enable a file mask  check which only  searches for files matching *.* or *.xxx extensions.   

You can download the source for DriveDemo here.