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  • #1

    How to detect first available drive for network?

    Fellows,

    How can a program (written in PBDLL60) detect which drive is the first available free logical drive for a network connection?
    Using GetDriveType, %DRIVE_REMOTE can only be detected when a connection has already been made.
    I remember from my 'good old' DOS age that you could pass a questionmark, in order to let the program find the first free drive letter. Is there a similar thing in Windows?

    Thanks a lot,
    Egbert

    ------------------
    mailto:[email protected][email protected]</A>
    www.basicguru.com/zijlema/

    Egbert Zijlema, journalist and programmer (zijlema at basicguru dot eu)
    http://zijlema.basicguru.eu
    *** Opinions expressed here are not necessarily untrue ***
    Tags: None
  • #2
    Here's some old code, written by me some time ago. It lists all used drive. If you change some things (and optimize it of course, because it's a bad solution), you can get the first free drive letter with it.

    Code:
    FUNCTION GetDrives () AS STRING 'alle vorhanden laufwerke auflisten
  LongVar& = GetLogicalDrives                  '(auch netzlaufwerke)
  FOR x& = 0 TO 25                             '1 f?r vorhanden, 0 f?r nicht vorhanden
    IF LTRIM$(STR$(BIT(LongVar&, x&),1)) = "1" THEN
       SELECT CASE x&
              CASE 0
                   a$ = "A:\"
              CASE 1
                   a$ = "B:\"
              CASE 2
                   a$ = "C:\"
              CASE 3
                   a$ = "D:\"
              CASE 4
                   a$ = "E:\"
              CASE 5
                   a$ = "F:\"
              CASE 6
                   a$ = "G:\"
              CASE 7
                   a$ = "H:\"
              CASE 8
                   a$ = "I:\"
              CASE 9
                   a$ = "J:\"
              CASE 10
                   a$ = "K:\"
              CASE 11
                   a$ = "L:\"
              CASE 12
                   a$ = "M:\"
              CASE 13
                   a$ = "N:\"
              CASE 14
                   a$ = "O:\"
              CASE 15
                   a$ = "P:\"
              CASE 16
                   a$ = "Q:\"
              CASE 17
                   a$ = "R:\"
              CASE 18
                   a$ = "S:\"
              CASE 19
                   a$ = "T:\"
              CASE 20
                   a$ = "U:\"
              CASE 21
                   a$ = "V:\"
              CASE 22
                   a$ = "W:\"
              CASE 23
                   a$ = "X:\"
              CASE 24
                   a$ = "Y:\"
              CASE 25
                   a$ = "Z:\"
       END SELECT

      'a$ contains the used drive. you can print it, add it to a listbox or whatever

     END IF                                                           
  NEXT
END FUNCTION
    ------------------
    E-Mail (home): mailto:[email protected][email protected]</A>
    E-Mail (work): mailto:[email protected][email protected]</A>

    Comment

    • #3
      An alternative would be to continue using GetDriveType, and use
      the first drive letter that returns %DRIVE_NO_ROOT_DIR. That's
      the standard result for drives not recognized by the OS. I don't
      *think* that the function ever returns %DRIVE_UNKNOWN for an
      unrecognized drive. It shouldn't, however, hurt to test for BOTH
      cases.

      Code:
      FOR A& = 67 TO 90
    B& = GetDriveType(CHR$(A&) + ":\")
    IF B& = %DRIVE_NO_ROOT_DIR THEN NewDrive$ = CHR$(A&) : EXIT FOR
NEXT A&
      Sven,

      Your code could be "tightened up" a bit by using the following
      instead of the SELECT CASE block:

      'use the following if the test returns TRUE for an invalid drive
      a$ = CHR$(Result& + 65) + ":\" : EXIT FOR

      Result& would be the return value by the test in the
      FOR/NEXT block. I apologize, but I can't remember most of the code
      that Sven posted, such as the variable names he used.

      Hope this helps, Egbert!

      ------------------
      Clay C. Clear
      http://www.v3space.com/a/a39/202/

      [email protected]
      [email protected]

      [This message has been edited by Clay Clear (edited July 05, 2001).]

      Comment

      • #4
        This is an addendum to my first reply:

        Sven's code might be better redone by using:

        'code for getting logical drive information goes here

        Code:
        FOR A& = 0 TO 25
    IF ISTRUE BIT(LongVar&, A&) THEN
       NewDrive$ = CHR$(A& + 65) + ":\" : EXIT : EXIT
    END IF
NEXT A&
        Enjoy!


        ------------------
        Clay C. Clear

        http://www.v3space.com/a/a39/202/

        [email protected]
        [email protected]

        Comment

        • #5
          This is what I head laying around:

          Code:
          FUNCTION AvailableDrive() AS STRING
  LOCAL mask AS LONG, count AS LONG
  mask = 8 : count = 68                        ' mask and ASCII-code for drive D
  RetVal& = GetLogicalDrives()                 ' get drives in use
  IF RetVal& = 0 THEN                          ' error
    FUNCTION = STR$(RetVal&)
'    FUNCTION = RetVal&
    EXIT FUNCTION
  END IF
  DO WHILE (RetVal& AND mask) <> 0
    mask = mask * 2                            ' next bit
    INCR count                                 ' next drive letter
    IF count > 90 THEN                         ' > Z? There are no more, folks!
      FUNCTION = "0"
      EXIT FUNCTION
    END IF
  LOOP
  SELECT CASE count
         CASE 68
              FUNCTION="D:"
         CASE 69
              FUNCTION="E:"
         CASE 70
              FUNCTION="F:"
         CASE 71
              FUNCTION="G:"
         CASE 72
              FUNCTION="H:"
         CASE 73
              FUNCTION="I:"
         CASE 74
              FUNCTION="J:"
         CASE 75
              FUNCTION="K:"
         CASE 76
              FUNCTION="L:"
         CASE 77
              FUNCTION="M:"
         CASE 78
              FUNCTION="N:"
         CASE 79
              FUNCTION="O:"
         CASE 80
              FUNCTION="P:"
         CASE 81
              FUNCTION="Q:"
         CASE 82
              FUNCTION="R:"
         CASE 83
              FUNCTION="S:"
         CASE 84
              FUNCTION="T:"
         CASE 85
              FUNCTION="U:"
         CASE 86
              FUNCTION="V:"
         CASE 87
              FUNCTION="W:"
         CASE 88
              FUNCTION="X:"
         CASE 89
              FUNCTION="Y:"
         CASE 90
              FUNCTION="Z:"
         CASE ELSE
              FUNCTION=""
    END SELECT
'  FUNCTION = count
END FUNCTION
          Think it needs no further comment.



          ------------------
          Herman
          You gotta walk and don't loop back.
          You gotta run, and don't loop back.

          Comment

          • #6
            Herman, an optimisation - replace this:
            Code:
              SELECT CASE count
         CASE 68
              FUNCTION="D:"
         CASE 69
              FUNCTION="E:"
         CASE 70
              FUNCTION="F:"
         CASE 71
              FUNCTION="G:"
         CASE 72
              FUNCTION="H:"
         CASE 73
              FUNCTION="I:"
         CASE 74
              FUNCTION="J:"
         CASE 75
              FUNCTION="K:"
         CASE 76
              FUNCTION="L:"
         CASE 77
              FUNCTION="M:"
         CASE 78
              FUNCTION="N:"
         CASE 79
              FUNCTION="O:"
         CASE 80
              FUNCTION="P:"
         CASE 81
              FUNCTION="Q:"
         CASE 82
              FUNCTION="R:"
         CASE 83
              FUNCTION="S:"
         CASE 84
              FUNCTION="T:"
         CASE 85
              FUNCTION="U:"
         CASE 86
              FUNCTION="V:"
         CASE 87
              FUNCTION="W:"
         CASE 88
              FUNCTION="X:"
         CASE 89
              FUNCTION="Y:"
         CASE 90
              FUNCTION="Z:"
         CASE ELSE
              FUNCTION=""
    END SELECT
            With this:
            Code:
             SELECT CASE count
  CASE 67 - 90: FUNCTION = CHR$(count) & ":"
  CASE ELSE: FUNCTION = ""
 END SELECT



            ------------------
            -

            Comment

            • #7
              Thanks for al your fast help, guys!

              Essentially it is the following: if GetDriveType() returns %DRIVE_NO_ROOT_DIR it is 'bingo!' I simply did not know the meaning of that value..
              Here is my contribution. I prefer a long integer (i.e. the drive letter's ascii code) in return, in order to create more flexibility in my application..

              Code:
              FUNCTION FirstFreeDrive() AS LONG
  LOCAL aski AS LONG, dType AS LONG
  aski = 67
  DO
    INCR aski                                       ' start with D:\
    IF aski > 90 THEN
      MSGBOX "No free drive found", 16, "Error"
      EXIT FUNCTION                                 ' stop searching
    END IF
    dType = GetDriveType(CHR$(aski) + ":\")
  LOOP UNTIL dType = %DRIVE_NO_ROOT_DIR
  FUNCTION = aski
END FUNCTION
              ------------------
              mailto:[email protected][email protected]uru.com</A>
              www.basicguru.com/zijlema/

              Egbert Zijlema, journalist and programmer (zijlema at basicguru dot eu)
              http://zijlema.basicguru.eu
              *** Opinions expressed here are not necessarily untrue ***

              Comment

              • #8
                Glad to help, Egbert!

                I'm posting this final reply to this topic to give you additional
                notes about using GetDriveType. The note is:

                GetDriveType will also return %DRIVE_NO_ROOT_DIR on any floppy
                drive (drives a: or b that doesn't exist. So, if your only
                use of it in a particular program is to check for available
                Network drives, then start your loop with ASC("C"). if you start
                at the bottom with ASC("A"), then it will erroneously report the
                first available drive as one of the floppy drives, if you don't
                have both floppy drive letters already in use by the system.




                ------------------
                Clay C. Clear

                http://www.v3space.com/a/a39/202/

                [email protected]
                [email protected]

                Comment

                • #9
                  The BFF code on my site uses com to enum objects.
                  If you are desperate you could use that one


                  ------------------
                  hellobasic

                  Comment

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