From: Peter Vandenabeele <peter@...>
Date: 2011-09-30T07:32:37+09:00
Subject: Re: IO.readlines will not accept variable with file name Why?

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On Thu, Sep 29, 2011 at 11:20 PM, Joda jenson <jodajen2@yahoo.com> wrote:

> Peter Vandenabeele wrote in post #1024266:
> > On Thu, Sep 29, 2011 at 10:39 PM, Joda jenson <jodajen2@yahoo.com>
> > wrote:
> >
> >> >>
> >> > puts filearray [0]
> >> Thanks for the help on this sorry for the typo, it was really late when
> >> I
> >> was posting.
> >>
> >> What is the easiest why to get the "\n" off the end?
> >>
> >
> > Look at chomp
> >
> > peterv@ASUS:~$ irb
> > 001:0> a = gets
> > test
> > => "test\n"
> > 002:0> a.chomp
> > => "test"
> > 003:0>
> >
> > HTH,
> >
> > Peter
>
> Peter is there any difference between chomp and
> This:
> string = string.gsub(/\n/," ")
> chomp looks easier to remember.
>

Well yes, a lot of difference ...

gsub(/\n/, "") will produce a new string, where occurences of a newline
character ("\n") are replaced with a space.

chomp will remove the last newline/carriage return combination
(0 or 1 CR and 0 or 1 LF if I am right).

003:0> b = "\nabc\ndef\n\nghi\n\n\n"
=> "\nabc\ndef\n\nghi\n\n\n"
004:0> b.chomp
=> "\nabc\ndef\n\nghi\n\n"
005:0> b.gsub(/\n/," ")
=> " abc def  ghi   "
006:0> c = "abc\r"
=> "abc\r"
007:0> c.chomp
=> "abc"
008:0> d = "abc\r\n"
=> "abc\r\n"
009:0> d.chomp
=> "abc"
010:0> d.gsub(/\n/," ")
=> "abc\r "
peterv@ASUS:~$ ruby -v
ruby 1.9.2p290  (2011-07-09 revision 32553) [i686-linux]

E.g. googling for "ruby chomp documentation" led me to this entry:

    http://ruby-doc.org/core/classes/String.html#M001188

For understanding regular expressions exactly, that needs a little
more study (but very rewarding).

Use irb (or pry) to test for yourself what the different behaviors are,
that's how you will really understand how it works.

HTH,

Peter

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