From: Todd Benson <caduceass@...>
Date: 2008-09-29T12:54:58+09:00
Subject: Re: .getc.chr doesn't work

On Sun, Sep 28, 2008 at 7:59 PM, Procek <proc.procek@gmail.com> wrote:
> Hi!
>
> I'm trying to read a file using ruby. Firsty I use readline twice,
> then I wan't to read some part of data, but I don't get where I have a
> mistake. Could you help me find it?
>
> ######## CUT HERE ########
> #Constans
> FS = 0x1c
> RS = 0x1e
>
> #Open file
> f = File.new("abcdef", "r")
>
> #Read a line, split it, and delete bad fields (last one)
> tbl = f.readline(FS.chr).split(RS.chr) - [FS.chr]
> #For each from tbl
> tbl.each { |x|
>   #Split field
>   splitted = x.split("_")
>   #The read loop
>   tmp = String.new
>   i=0
>   while (i < splitted[2].to_i)
>     tmp += f.getc.chr #Here I have an error...
>   end
>   #Save readed data
>   f2 = File.new(s[0]+"-"+s[1]+".txt", "w")
>   f2.write(tmp)
>   f2.close
> }
>
> #Close file
> f.close
> ######## CUT HERE ########
>
> The test file in HEX (beacouse it have non-printable chars)
> ######## CUT HERE ########
> 31 37 31 5f 35 31 32 5f 31 32 1e 33 30 34 5f 35 31 32 5f 39 1e 1c 61
> 62 63 64 65 66 67 68 69 6a 6b 6c 30 31 32 33 34 35 36 37 38
> ######## CUT HERE ########

I'm not sure exactly what you are trying to do, but I have a guess.  I
wouldn't really use readline or getc for this...


FS = 0x1c
RS = 0x1e

#your hex string
hex = "31 37 31 5f 35 31 32 5f 31 32 1e 33 30 34 5f 35 31 32 5f 39 /
 1e 1c 61 62 63 64 65 66 67 68 69 6a 6b 6c 30 31 32 33 34 35 36 37 38"

#change it to your real data
s = hex.split.map {|i| i.to_i(16).chr}.join
#=> "171_512_12\036304_512_9\036\034abcdefghijkl012345678"

info, data = s.split(FS.chr)
lengths = info.split(RS.chr).map {|i| i.split(/_/).last}
data_array = []
lengths.each {|len| data_array << data.slice!(0, len.to_i)}

p data_array


...Your test file isn't long enough for me to establish  the actual
layout, so I had to make educated guesses.  When reading a file you
can wrap your code up like...


File.open( 'my_file', 'r') do |f|
  #parsing code in here
end


hth,
Todd