From: Robert Klemme <shortcutter@...>
Date: 2008-06-26T21:43:53+09:00
Subject: Re: How to find second match in a file

2008/6/25 Cheyne Li <happy.go.lucky.clr@gmail.com>:
> Hi, everyone
>
> My code opens a file and read line by line to find a given string as
> first match. After I found one, how can i find the second match, a
> different string, which is supposed to appear several lines after the
> line of first match in a fast way?
>
> for example, the following is the contents of a file
>
> ka;sdfjaskf;asdfjk
> skdfkfkfkfkfkfkfkfkfk
> aks;flasjklfjkassjfksa
> aaaaaaaaaaaaaaaaaaaaaaaa
> bbbbbasdfdask;fjsdkalf
> *************hello world***************ka;sdjkf;sjadkfj
> asdfkasjdkfldjaskl;jfklas;
> jaskdl;fjkasdjkfljdskla;jdfs
> jkasl;jfkasjdklfjsal;df
> asjkdfjkasd;fd;asdfj
> ***********Ruby*********a;sjdfklsdjal;fjkda;
> asdfjjasklfjkdasjkfjaskl;
> fjdka;dfdjasjfsd;a
>
> So, after I found the match "hello world" by using a while loop, how can
> i find the "Ruby" in the same while loop?

It's probably easiest if you store the state of your search somewhere.

state = :initial

File.foreach "foo" do |line|
  case state
  when :initial
    if /first/ =~ line
      puts line
      state = :first_match
    end
  when :first_match
    if /second/ =~ line
      puts line
      state = :second_match
    end
  else
    # ignore
  end
end

Cheers

robert


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