Q125372: How To Check for a Floppy Disk Using FOXTOOLS

Article: Q125372
Product(s): Microsoft FoxPro
Version(s): 2.6x 3.00 3.00b
Operating System(s): 
Keyword(s): 
Last Modified: 20-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b 
- Microsoft FoxPro for Windows, version 2.6x 
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SUMMARY
=======

The code in this article demonstrates how to use FOXTOOLS.FLL to register and
call Windows API functions that check the floppy drive to determine if a disk is
present.

MORE INFORMATION
================

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.

Additional query words: VFoxWin FoxWin kbinf 2.60 2.60a

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Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbFoxproSearch kbVFP300 kbVFP300b
Version           : 2.6x 3.00 3.00b

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