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awesomej01

Sun May 30, 2004 4:22 pm


opening files

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I'm trying to write an algorithm that can take a file for eg. abc and open it then output it as cba.  I tried putting it into a for decreasing loop but that didn't work, then I tried using a normal loop but that didn't work either.  If  anyone don't mind I hope they can tell me what is wrong with my code and help me fix it. thanks.

var filestream : int
var words : string
var CountingThingy2, CountingThingy : int := 0

%Count how many characters are in the file
open : filestream, "temp.txt", get
loop
    exit when eof (filestream)
    get : filestream, words : 1
    CountingThingy := CountingThingy + 1
end loop
close : filestream
put CountingThingy

%Method 1
open : filestream, "temp.txt", get
loop
    get : filestream, words : 1
    CountingThingy2 := CountingThingy2 + 1
    if CountingThingy2 = CountingThingy then
        put words ..
        CountingThingy2 := 0
        CountingThingy := CountingThingy - 1
    end if
    exit when CountingThingy = 0
end loop
close : filestream

%Method 2
open : filestream, "temp.txt", get
for decreasing i : CountingThingy .. 1
    get : filestream, words : 1
    put words ..
end for
close : filestream

Neither of these methods work.


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Delos

Sun May 30, 2004 4:33 pm



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Wow...this code is...wow

Ok.  First things first.

1)  use [ code][/code] tags.
2)  you may want to have attatched the 'temp.txt' file of which you speak.  We could always create one for ourselves...but that could be tedious...

- you are getting one letter at a time...why!  That makes your life difficult.  Your initial little piece there, the one that counts the number of letters in the file, also counts the eof...so that's no good.  Just get the entire line (using :*) and then length() it.
- once you have the required file contents in a string, reversing it is no problem...just use a (decresing) for loop...nothing difficult.
- if you need to write this new string to a file, put: will do fine.

Try that, then repost if you're still on a limb...or two...


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naoki

Sun May 30, 2004 9:43 pm



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so you want "abc" to become "cba"?

like delos stated, your method is very inefficient. getting from a text file one letter at a time is very time consuming and kinda slow.

why don't you get a whole line ( get: file, word : *) and then go through a for loop (again, like delos stated) from 1 .. length (word).

then make a temporary string holder (tempword) and add one letter at a time from word to tempword


get: file, word : *
for x : 1 .. length (word)
   tempword += word (length (word) - x)
end for
put: file2, tempword


[/code]


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McKenzie

Tue Jun 01, 2004 7:22 am



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I'm trying to write an algorithm that can take a file for eg. abc and open it then output it as cba.
Seems he wants the whole file reversed, not just each line of the file reversed in and of itself.

Well, the two good things about reading from a file one character at a time are:
1. You don't have a problem at the end of file (can't skip past)
2. More importantly you preserve the exact file and file size. When you read with standard token based input you don't know if there is a single space, 20 spaces a tab ... between your tokens. 

To read things backwards use seek. eg.

var fp:int
var sz:int:=0
var ch:string(1)

open :fp,"punk.txt",get,seek
seek:fp,*
tell:fp,sz

for decreasing i:sz-1..0
    seek:fp,i
    get:fp,ch:1
    put ch..
end for
close:fp


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TheZsterBunny

Wed Jun 02, 2004 4:19 pm



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It strikes me as odd that awesomeJ isn't using a simple 2d array of individual chars rather than all those files.

It's pretty cool, the way you've done it and all, but you didn't have to.

oh, and mckenzie, when is your lesson on hashing?

-Z


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McKenzie

Wed Jun 02, 2004 10:14 pm



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Catch me in the morning on hashing. If not I'll have to pull myself away from Heroclix and do it after school.