How To Check for a Floppy Disk Using FOXTOOLS (125372)

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There is no single FoxPro command that determines if a floppy disk drive is empty. Fortunately, several third-party and shareware routines exist to perform this function. However, most of these routines were written for use with FoxPro for MS-DOS.

The following code example employs FOXTOOLS.FLL to register and call Windows API functions that check the floppy drive for a disk and return an error message if the disk drive is empty.

   * Function isdiskin - determine if a specified disk is present in
   * FoxPro for Windows
   *
   * passed: drive letter, in the form of <drive letter A-Z> or
   * <drive letter A-Z:>
   * returns: logical .t. if disk can be read, .f. if it cannot
   *
   *    example:
   *    IF isdiskin("A:")
   *      WAIT WINDOW "There is a disk in drive A:"
   *    ENDIF

   FUNCTION isdiskin

   PARAMETERS m.drive

   * test passed drive letter - is it greater than 2 characters,
   * blank, or outside the range of A-Z? If so, then return .f.
   m.drive = ALLTRIM(m.drive)
   IF LEN(m.drive) > 2 .OR. LEN(m.drive) = 0 .OR. .NOT. ;
   BETWEEN(ASC(UPPER(m.drive)), 65, 90)
   RETURN .f.
   ENDIF

   IF RIGHT(m.drive,1) # ":"
      m.drive = m.drive + ":"
   ENDIF

   * detect if FOXTOOLS.FLL is already loaded; if not, load it
   m.isloaded = "FOXTOOLS" $ SET("LIBRARY")
   IF .NOT. m.isloaded
      SET LIBRARY TO SYS(2004)+"FOXTOOLS.FLL" ADDITIVE
   ENDIF

   * detect if another error routine is already present, save its name
   m.olderror = ON('error')
   ON ERROR DO diskerr

   * hang onto the old error mode for later restoration
   m.seterrmode = REGFN("SetErrorMode", "I", "I")

   * SetErrorMode with an argument of 1 causes Windows to relinquish
   * critical error handling back
   * to the application, which ideally does a DOS
   * GetExtendedErrorInformation call to determine
   * the nature of the error. FoxPro doesn't do this, only recognizes
   * that the error has occurred
   * and so calls the ON ERROR routine with an error() value of 0.
   m.olderrstate = CALLFN(m.seterrmode,1)

   * default is no disk errors; our ON ERROR routine sets this variable
   m.diskerr = .f.

   * try to find the NUL file in the root of the passed drive
   m.drivestate = FILE(m.drive + "\NUL")

   IF .NOT. m.diskerr
      * no disk error, so what did the file() call return?
      IF m.drivestate
      m.driveok = .t.
      ELSE
      m.driveok = .f.
      ENDIF
   ELSE
      m.driveok = .f.
   ENDIF

   * restore the old error handler, old error state, old library state
   * and old talk state
   IF .NOT. EMPTY(m.olderror)
      ON ERROR DO (m.olderror)
   ELSE
      ON ERROR
   ENDIF

   m.resterrstate = CALLFN(m.seterrmode,m.olderrstate)

   IF .NOT. m.isloaded
      RELEASE LIBRARY SYS(2004)+"FOXTOOLS.FLL"
   ENDIF

   RETURN m.driveok

   * FoxPro thinks the error() is 0 after the failed file() call with
   *SetErrorMode = 1. Just set
   * our m.diskerr variable .t. on any error
   PROCEDURE diskerr

   m.diskerr = .t.