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comp.lang.ruby

Problem reading small files - stringio problem?

Singeo

5/27/2008 11:38:00 AM

Hi, I wonder if someone can take a quick look at this code and tell me
where I'm going wrong. The small files (less than 20k?) that I read in
this array are not appearing in the output file. I understand this is
a problem to do with stringio but have not found a way to fix it.
Thanks.

letters=("A".."Z").to_a
link_array = []

for index in (0...letters.length)
dummy = letters[index] + ".html"
link_array << dummy
end

open('sample.txt','w')
for index in (0...link_array.length)
guide=File.open(link_array[index], "r+")
html = guide.read
open('sample.txt','a') do |f|
f.puts guide
end
end
3 Answers

Martin Boese

5/27/2008 12:49:00 PM

0

I think your problem is: open('sample.txt', 'w'). You either open a file for
append or write, but not both. Remove this line and it might work.

Shorter also might be:

File.open('sample.txt', 'a') do |out|
('A'..'Z').each do |c|
out.puts File.open("#{c}.html", 'r').read
end
end


martin


On Tuesday 27 May 2008 12:37:37 Singeo wrote:
> Hi, I wonder if someone can take a quick look at this code and tell me
> where I'm going wrong. The small files (less than 20k?) that I read in
> this array are not appearing in the output file. I understand this is
> a problem to do with stringio but have not found a way to fix it.
> Thanks.
>
> letters=("A".."Z").to_a
> link_array = []
>
> for index in (0...letters.length)
> dummy = letters[index] + ".html"
> link_array << dummy
> end
>
> open('sample.txt','w')
> for index in (0...link_array.length)
> guide=File.open(link_array[index], "r+")
> html = guide.read
> open('sample.txt','a') do |f|
> f.puts guide
> end
> end

Robert Klemme

5/27/2008 12:53:00 PM

0

2008/5/27 Singeo <singeo.sg@gmail.com>:
> Hi, I wonder if someone can take a quick look at this code and tell me
> where I'm going wrong. The small files (less than 20k?) that I read in
> this array are not appearing in the output file. I understand this is
> a problem to do with stringio but have not found a way to fix it.
> Thanks.
>
> letters=("A".."Z").to_a
> link_array = []
>
> for index in (0...letters.length)
> dummy = letters[index] + ".html"
> link_array << dummy
> end
>
> open('sample.txt','w')
> for index in (0...link_array.length)
> guide=File.open(link_array[index], "r+")
> html = guide.read
> open('sample.txt','a') do |f|
> f.puts guide
> end
> end

This has nothing to do with StringIO. You do not close all your file
descriptors properly. You should make it a habit to use the block
form of File.open.

Note also that you can use ("A" .. "Z") directly for iterating. Also,
it does not make sense to open and close "sample.txt" all the time.
Also, why do you write the IO object to the file and not the content?
It seems your code can be achieved by doing this:

File.open("sample.txt", "a") do |out|
for ch in "A".."Z"
out.write(File.read(ch + ".html"))
end
end

If your files are larger, you should copy chunkwise

File.open("sample.txt", "a") do |out|
for ch in "A".."Z"
File.read(ch + ".html") do |in|
while buffer = in.read(1024)
out.write buffer
end
end
end
end


Kind regards

robert

--
use.inject do |as, often| as.you_can - without end

Singeo

5/27/2008 4:27:00 PM

0

Martin/Robert, thank you both for your quick replies. Both your
suggestions work, thanks for the valuable advice.

I'm still puzzled as to why my code (however bad....) was working with
all but the smaller files (5 of the 26 all less than 20k)). But I can
now move forward.

Regards

Singeo



On May 27, 8:52=A0pm, "Robert Klemme" <shortcut...@googlemail.com>
wrote:
> 2008/5/27 Singeo <singeo...@gmail.com>:
>
>
>
> > Hi, I wonder if someone can take a quick look at this code and tell me
> > where I'm going wrong. The small files (less than 20k?) that I read in
> > this array are not appearing in the output file. I understand this is
> > a problem to do with stringio but have not found a way to fix it.
> > Thanks.
>
> > letters=3D("A".."Z").to_a
> > link_array =3D []
>
> > for index in (0...letters.length)
> > =A0dummy =3D letters[index] + ".html"
> > =A0link_array << dummy
> > end
>
> > open('sample.txt','w')
> > for index in (0...link_array.length)
> > =A0guide=3DFile.open(link_array[index], "r+")
> > =A0html =3D guide.read
> > =A0open('sample.txt','a') do |f|
> > =A0 =A0f.puts guide
> > =A0end
> > end
>
> This has nothing to do with StringIO. =A0You do not close all your file
> descriptors properly. =A0You should make it a habit to use the block
> form of File.open.
>
> Note also that you can use ("A" .. "Z") directly for iterating. =A0Also,
> it does not make sense to open and close "sample.txt" all the time.
> Also, why do you write the IO object to the file and not the content?
> It seems your code can be achieved by doing this:
>
> File.open("sample.txt", "a") do |out|
> =A0 for ch in "A".."Z"
> =A0 =A0 out.write(File.read(ch + ".html"))
> =A0 end
> end
>
> If your files are larger, you should copy chunkwise
>
> File.open("sample.txt", "a") do |out|
> =A0 for ch in "A".."Z"
> =A0 =A0 File.read(ch + ".html") do |in|
> =A0 =A0 =A0 while buffer =3D in.read(1024)
> =A0 =A0 =A0 =A0 out.write buffer
> =A0 =A0 =A0 end
> =A0 =A0 end
> =A0 end
> end
>
> Kind regards
>
> robert
>
> --
> use.inject do |as, often| as.you_can - without end