Read in file

Ruby
1

Hi,
I’ve created a simple program which will read in a file.

class Reference
references = ‘C:\Documents and Settings\Chris
Davies\Desktop\References.rb’

f = File.open(references, ‘r’)
file_data = f.read
f.close

puts file_data
end

but i want to take this file data and interpret each line of data and
the put each line into a new file line by line.

cheers

2

Chris Daves wrote:

Hi,
I’ve created a simple program which will read in a file.

class Reference
references = ‘C:\Documents and Settings\Chris
Davies\Desktop\References.rb’

f = File.open(references, ‘r’)
file_data = f.read
f.close

puts file_data
end

but i want to take this file data and interpret each line of data and
the put each line into a new file line by line.

cheers

File.open(“path/your/file”) do |sFile|
while sLine = sFile.gets
puts YouCanSeeYourData
end
end

3

Junyoung Kim wrote:

Chris Daves wrote:

Hi,
I’ve created a simple program which will read in a file.

class Reference
references = ‘C:\Documents and Settings\Chris
Davies\Desktop\References.rb’

f = File.open(references, ‘r’)
file_data = f.read
f.close

puts file_data
end

but i want to take this file data and interpret each line of data and
the put each line into a new file line by line.

cheers

File.open(“path/your/file”) do |sFile|
while sLine = sFile.gets
puts YouCanSeeYourData
end
end

cheers for that, but how can i take that data and move it into a new
file line by line? i just want to move exactly the same data from an
existing file to a new file.

cheers

4

if you dont want to modify the existing file, you dont need to open
file. just duplicate it or copy it.

in my case, i will use fileutils(cp_r methods is only available on 1.8)

example)

require ‘fileutils’

include FileUtils

cp_r “existing”, “new”

5

Or if you do want to read and modify it…

new = File.open(‘filetowriteto’, ‘w’)
File.foreach(‘oldfile’) do |line|
new.puts line

…

end

or…

File.open(‘newfile’, ‘w’) do |file|
file.puts File.read(‘oldfile’)
end

or…

There are many ways, check out File# and FileUtils

Regards,
Lee

6

another way…

File.open(‘out.txt’, ‘w’) do |out|
File.open(‘test.txt’, ‘r’).each do |line|
out.puts line if (line.size > 4)
end
end

Here are some ways to pull each line from a file in other languages:
http://blog.huikau.com/2007/11/25/simple-file-io-in-different-dynamic-languages/

M

On Dec 13, 2007 9:54 AM, Sebastian H. [email protected]

7

Mike McKinney wrote:

File.open(‘out.txt’, ‘w’) do |out|
File.open(‘test.txt’, ‘r’).each do |line|
out.puts line if (line.size > 4)
end
end

That leaves test.txt open which is not good. Don’t use File.open in
chains
like that. Or better yet: Don’t use File.open without a block at all.

HTH,
Sebastian

8

Chris Daves wrote:

f = File.open(references, ‘r’)
file_data = f.read
f.close

That can be written as
file_data=File.read(“references”)
It’s generally better not to use File in a way that you have to manually
close
the file.

but i want to take this file data and interpret each line of data and
the put each line into a new file line by line.

File.open(outfile, “w”) do |of|
File.foreach(infile) do |line|
do_something_with line
of.puts line
end
end

HTH,
Sebastian

9

On Dec 13, 10:29 am, Phrogz [email protected] wrote:

That leaves test.txt open which is not good. Don’t use File.open in chains
like that. Or better yet: Don’t use File.open without a block at all.

He is using the block form of File.open, which is guaranteed to close
the file at the end. Right?

Nevermind; my reading comprehension seems to be turned off this
morning.

10

very good point!

On Dec 13, 2007 10:27 AM, Sebastian H. [email protected]

11

On Dec 13, 8:27 am, Sebastian H. [email protected]
wrote:

Mike McKinney wrote:

File.open(‘out.txt’, ‘w’) do |out|
File.open(‘test.txt’, ‘r’).each do |line|
out.puts line if (line.size > 4)
end
end

That leaves test.txt open which is not good. Don’t use File.open in chains
like that. Or better yet: Don’t use File.open without a block at all.

He is using the block form of File.open, which is guaranteed to close
the file at the end. Right?