From: John Sikora <john.sikora@...>
Date: 2010-10-04T12:56:34+09:00
Subject: Re: save only first line from string?

Terry Michaels wrote:
> Hi. What's the most simple and elegant way to remove all the contents of
> a String except for the first line? (Assume string consist of one line,
> multiple lines, or no lines, and assume that we don't know which OS we
> are on.)

I don't know about the most elegant or simple way, but how about this:

string.sub!(/^(.*\n?)((?im).+)?/, '\1').chomp

Some tests:

string_1 = <<END_OF_STRING_1
hello there.
how is it going?
END_OF_STRING_1

string_2 = "hi there\n"
string_3 = "\n"
string_4 = 'hi'
string_5 = ''

regex = /^(.*\n?)((?im).+)?/

p string_1.sub!(regex, '\1').chomp # => "hello there."
p string_2.sub!(regex, '\1').chomp # => "hi there"
p string_3.sub!(regex, '\1').chomp # => ""
p string_4.sub!(regex, '\1').chomp # => "hi"
p string_5.sub!(regex, '\1').chomp # => ""


I don't think that the ^ is really needed, but I included it anyway. 
Also, don't be surprised if someone finds a fault with this or comes up 
with a better solution (I never figured I would be giving advice on 
regexs).

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