HOWTO: Determine the Logical Drives on a System

• Microsoft Visual FoxPro for Windows, version 6.0

SUMMARY

You can use the GetLogicalDrives() API function to find which logical drives are present in a system. The GetLogicalDrives() function returns a 32-bit value in which each bit represents whether the logical drive exists. For example, if the system has an A drive, bit 0 will be set, and if the system has a drive Z, bit 25 will be set.

MORE INFORMATION

The following program demonstrates the use of the GetLogicalDrives() API function. The sample program calls the function and loops through each bit of the return value, using the FoxPro Bittest() function to determine if a particular drive is present or not. It displays all the drives on the system and their drive types in a message box.

Sample Code

   * This program enumerates all drives on a Win32 system and
   * displays a message box containing the drive letters and
   * types of all logical drives on the system.
   *

   * Constants for drive types.
   #DEFINE DRIVE_UNKNOWN 0
   #DEFINE DRIVE_NO_ROOT_DIR 1
   #DEFINE DRIVE_REMOVABLE 2
   #DEFINE DRIVE_FIXED 3
   #DEFINE DRIVE_REMOTE 4
   #DEFINE DRIVE_CDROM 5
   #DEFINE DRIVE_RAMDISK 6
   #DEFINE CR CHR(13)

   DECLARE INTEGER GetLogicalDrives IN Win32API
   DECLARE INTEGER GetDriveType IN Win32API STRING RootPath

   PRIVATE lcDrivestring, lcDriveRoot, liDrivelist, lcDrives, i
   lcDrives = ""

   * GetLogicalDrives returns a 32-bit value containing a list of
   * available drives. If the specific bit is ON, the drive letter
   * corresponding to that position exists.
   liDrivelist = GetLogicalDrives()

   * Check each of the bits
   FOR i = 0 TO 31
      IF BITTEST(liDrivelist, i)
   * If the 0th bit is ON, that means drive 'A:',
   * the 2nd bit is 'C:", etc.
         lcDriveRoot = CHR(65 + i) + ":\"
   * Perform a GetDriveType to determine if it is a floppy, CD, etc.
         lcDrivetype = GetDriveType(lcDriveRoot)
         DO CASE
            CASE lcDrivetype = DRIVE_UNKNOWN
               lcDrivestring = "Cannot be determined"
            CASE lcDrivetype = DRIVE_NO_ROOT_DIR
               lcDrivestring = "Root directory does not exist"
            CASE lcDrivetype = DRIVE_REMOVABLE
               lcDrivestring = "Floppy/removable drive"
            CASE lcDrivetype = DRIVE_FIXED
               lcDrivestring = "Hard drive/nonremovable drive"
            CASE lcDrivetype = DRIVE_REMOTE
               lcDrivestring = "Remote/Network drive"
            CASE lcDrivetype = DRIVE_CDROM
               lcDrivestring = "CD-ROM drive"
            CASE lcDrivetype = DRIVE_RAMDISK
               lcDrivestring = "RAM disk"
         ENDCASE
         lcDrives = lcDrives + lcDriveRoot + " " + lcDrivestring + CR
      ENDIF
   NEXT

   =MESSAGEBOX(lcDrives, ;
      0 + 64 + 0) 

REFERENCES

"Advanced Windows", Third Edition, Jeffrey Richter, pages 615-695, Microsoft Press, 1997.

Additional query words: kbVFp600 kbAPI

Keywords :
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbhowto