Getting file atributes (FilesEx and Bitwise)

Discussion in 'Questions (Windows Mobile)' started by Mr_Gee, Aug 29, 2008.

  1. Mr_Gee

    Mr_Gee Active Member Licensed User

    Hi All,

    I've been wrestling with this for a couple of day now, and it's really annoying me.

    I'm trying to get and set the file properties, but i'm getting very inconsistent results..

    I want to make sure the file is not readonly, hidden, system file etc.

    According to Agraham the FilesEx needs the Bitwise.dll to be able to view the properties

    I can understand that a file has a couple of bytes in which the properties are set, but i cant seem to get this info :-(

    Can anyone point me in the right direction?
    Below is a part of the code I used to test

    Sub read
       item1 = Fex.FileGetAttributes(FileLoc& 
    "readonly - "&bit.GetBit(item1,1))
    "hidden - "&bit.GetBit(item1,2))
    "system - "&bit.GetBit(item1,4))
    "normal - "&bit.GetBit(item1,128))
    End Sub    
    Sub write   
    End Sub
    I've also tried bit.GetBit(X,Y) and bit.GetBit(Y,X) (reverse the two)
    also didn't do much ..


  2. agraham

    agraham Expert Licensed User

    Firstly your bit numbering is wrong, you are using the numeric value of a bit and not the bit position. It should be -
    item1 = FilesEx1.FileGetAttributes(AppPath & "\test1.txt")
       msg = item1 & 
       msg = msg & 
    "readonly - "bit.GetBit(item1,0) & CRLF
       msg = msg & 
    "hidden - "  & bit.GetBit(item1, 1) & CRLF
       msg = msg & 
    "system - " & bit.GetBit(item1, 2) & CRLF
       msg = msg & 
    "normal - " & bit.GetBit(item1, 7)   & CRLF
    Bit No, Value 0,1 : 1,2 : 2,4 : 3,8 : 4,16 : 5, 32 : 6,64 : 7,128 ...

    Secondly you can't set attributes individually, they are all set at at once. Set the bits that you want and do a single Set.

    item1 = FilesEx1.FileGetAttributes(AppPath & "\test1.txt")
       item1 = 
    Bit.SetBit(item1, 0' original attributes plus the readonly bit
       FilesEx1.FileSetAttributes(AppPath & "\test1.txt",item1) ' make it readonly
  3. Mr_Gee

    Mr_Gee Active Member Licensed User

    Thanks Agraham,

    Just so I understand correctly in your example

    item1 holds the bits
    gets the value of bit 0 in item1

    bit.GetBit(item1, 7)
    gets the value of bit 7 in item1


    so basically it it states bit.GetBit(input_stream , bit_index )

    Do the bits look look this : item1 = "11111111" or like
    item1 = "1,2,4,16,32,64,128"

    If its the first so this makes sense, then they look a bit like a dipswitch ...
    If it is the second, I'm a bit unsure...

    what doesn't make sense is the setting of the attributes..
    why is it "Bit.SetBit(item1, 0)" ?

    When doing a MsgBox(item1) I also saw some different numbers
    32 & 33 etc..
    Is this the sum of the set bits in item1? (just like a binary clock,adding them together?)

    Bit.SetBit(item1, 7)
    would be readonly, hidden & system set to true

    Thanks for your help Agraham
  4. agraham

    agraham Expert Licensed User

    Yes, that is how numbers are held in a computer. Binary numeral system - Wikipedia, the free encyclopedia
    That is saying "set the bit position 0 of the number in item1". You would use ClrearBit to set it to 0.

    Yes, it would be the sum of the values of each bit position.

    No. That just sets bit position 7 (128) to 1 but "FilesEx1.FileSetAttributes(AppPath & "\test1.txt",7) " would do that. You must distinguish between the individual bits that GetBit and ClearBit deal with and the number that a collection of bits represents.
  5. Mr_Gee

    Mr_Gee Active Member Licensed User

    So a readonly file would be 10000000 ( position 1 set to true)
    and a normal file would be 00000001 ( position 7 set to true)
    hidden & readonly would be 11000000 ( position 1 & 2 set to true)

    So SetBit only allows you to set a certain bit (attribute) to true,
    to set it to false I would need to use bit.ClearBit(item1,XXX)
    where XXX is the position that will be set...

    Is it correct to assume that the two are the same (just more specific)?
    a readonly file saying ClearBit(item1,1) or
    "FilesEx1.FileSetAttributes(AppPath & "\test1.txt",7)"

    for a readonly & hidden file using the ClearBit(item1,1) would make it writable not visible while "FilesEx1.FileSetAttributes(AppPath & "\test1.txt",7)" would do both?

    I'm a huge :sign0104: in this area...sorry
  6. agraham

    agraham Expert Licensed User

    Conventionally binary numbers are writen with the same significance order as decimals and bit positions count from 0 so
    ...00000001 = readonly - position 0 not 1 set true
    ...00000011 = hidden and readonly - positions 0 and 1 set true
    ...10000000 = normal - position 7 set true - I have not seen this set
    No. One is clearing a bit in a variable, the other is assigning a set of attributes to a file.

    It's bit 0 not bit 1 that is the readonly attribute bit. Assuming item1 contained the original attribute set then ClearBit(item1,0) would make the file writeable but not visible once reassigned to the file. Assigning 7 to the file will make it readonly, hidden and system.
  7. Mr_Gee

    Mr_Gee Active Member Licensed User

    so the combined values for the above would be

    because that is the sum of 1, 2 and 4 :sign0060:

    so "FilesEx1.FileSetAttributes(AppPath & "\test1.txt",128) " Clears all attributes...

    I'm getting there :)

    I've attached my test file, maybe someone else can benefit from it
    I entered 0 & 7 , if I hit "set" then "read" it gives me a value of
    128 -> normal = true

    Thanks for your great explanation :sign0188:
    Let me get you a beer

    Attached Files:

  8. agraham

    agraham Expert Licensed User

    In a real app it is better to always read the attributes and just modify the ones you want to change. There are other attributes, the ones in bit positions greater than 3, that you should probably not meddle with unless you are going to delete the file immediately.
  9. Mr_Gee

    Mr_Gee Active Member Licensed User

    That's good advice

    something like
    item1 = FilesEx1.FileGetAttributes(AppPath & "\test1.txt")
    item1 = 
    Bit.ClearBit(item1, 0' removes readonly attribute
    item1 = Bit.ClearBit(item1, 1'  ' removes readonly attribute
    item1 = Bit.ClearBit(item1, 4'  ' removes System attribute
    FilesEx1.FileSetAttributes(AppPath & "\test1.txt",item1)
  10. agraham

    agraham Expert Licensed User

    Nearly, but bit 2 is the system bit, you have its value there!
  11. Mr_Gee

    Mr_Gee Active Member Licensed User

    cr*p.. so close

    I was looking at the FilesEx helpfile, indeed 4 is Directory

    I think I get it now, thanks again for your help and time.

    I'm going to play around a bit more
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