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timmytheturtle

Sun Sep 19, 2004 7:54 pm


Read and writing to a binary file

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What I need help with is im tryin to add names to a binary file using the read and write commands, I can get the name to write but it overwrites the first name in the file, How do I make it write the new name to the end of the list of names? Any help would be greatly appericated, thanks in advance

part of the code:

proc Output (var sn : int, var names : array 1 .. * of string (15))
    open : sn, "Names.bin", write
    assert sn > 0
    for i : 1 .. upper (names)
        write : sn, names (i)
    end for
    close : sn
end Output

proc OutputNames (var sn : int, var names : array 1 .. * of string (15))
    open : sn, "Names.bin", read
    for i : 1 .. upper (names)
        read : sn, names (i)
        put names (i)
    end for
    delay (1500)
    close : sn
end OutputNames

**This is were it writes the new name**
proc AddNames (var sn : int, var names : array 1 .. * of string (15))
    open : sn, "Names.bin", write, seek
    put "Enter the name to be added to the file"
    get names (lower (names))
    write : sn, names (lower (names))
    close : sn
end AddNames

%MainLine
View.Set ("graphics:600;800,nobuttonbar ")

var names : array 1 .. 5 of string (15) := init ("Chris", "Tom", "Steve", "Kevin", "Tim")
var sn : int
var choice : string (1)
loop
    MenU (choice)
    if choice = '1' then
        Output (sn, names)
    elsif choice = '2' then
        AddNames (sn, names)
   % elsif choice = '3' then
      %  ReplaceNames (names, sn)
    elsif choice = '5' then
        OutputNames (sn, names)
    elsif choice = 'e' or choice = 'E' then
        exit
    else
        put "not such option"
        delay (1000)
        cls
    end if
end loop



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Delos

Mon Sep 20, 2004 10:41 am



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Hmm...I'm not all to familiar w/ read/write (being a get:/put: person myself) but I think your problem lies in the fact that you're writing directly to the file.

Try to load the entire file into memory at one time, then get your changes, then edit them in memory, and then write them back into your file (clearing everything inside it first).
I'm not sure if this defeats your initial purpose or not though...but it does work.


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Tony

Mon Sep 20, 2004 1:14 pm



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no delos :lol: 

the point of random access is just that - access the file randomly :wink: 

if you want to write to the end of the file, you open it for :write, seek, mod and use seek:* to move to the end of the file. You can add new data there.

somebody confirm if this is right or now, I personally never used random access with turing


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timmytheturtle

Mon Sep 20, 2004 2:22 pm



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thanks for all your help, I hope it works.


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timmytheturtle

Mon Sep 20, 2004 2:40 pm



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I just tried it and no luck, it overwrites the first name, but if i put 5(number of names originally in file) it puts the new name with the first name and puts a bunch of characters in fron of the name in the second line. 

Edit: I got it to work, I did need to seek to the end of the file