This one's easy. You need to use the cunningly-named GetLogicalDriveStrings API.

   int    iStrsLen;
   char   smzDrives [(3+1)*26+1];
   char   szDrive   [3+1];
   int    i;

   iStrsLen = GetLogicalDriveStrings (sizeof(smzDrives), smzDrives);

   if (iStrsLen == 0)
   {
      // Handle error
   }
   else
   {
      if (iStrsLen > sizeof(smzDrives))
      {
         // Buffer not big enough... eh? - I provided space for all 26 !?!
      }
      else
      {
         // Parse the returned multi-string array.
         i = 0;
         while (smzDrives[i])
         {
            strcpy (szDrive, &(smzDrives[i]));
            // szDrive now contains the root folder of this drive. I
            // put this in a listbox here:
            m_ctrlListbox.AddString (szDrive);
            while (smzDrives[i]) i++;
            i++;
         }
      }
   }

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