From: Chris White <cwprogram@...>
Date: 2011-08-20T06:06:20+09:00
Subject: Re: Searching in a directory


On Aug 19, 2011, at 1:51 PM, Yu Yu wrote:

> This search-routine is part of a bigger script and I've problems with 
> this part. I try to keep it simple...
> 
> I'm looking for one string: dog
> 
> in all these files:
> 
> file 1:
> cat bird
> frog eagle
> 
> file2:
> dog cat
> eagle frog
> 
> file3:
> cat cat
> eagle bird
> dog bird
> 
> file4:
> ...
> 
> The search begins in file1. If the string dog is found in file2 the 
> search should stop. Thats all!

Ah, here's a way to do that:

 dir_path = './test_files'
 str = "dog"

 Dir.chdir(dir_path) do

 Dir.glob("*.txt").inject(false) do |found, filename|
   IO.foreach(filename) do |line|
     if line =~ /#{str}/
       puts "#{filename}: #{str}"
       if found == true
        puts "Second instance found"
        exit # or however you want to handle this
       else
        found = true
       end
     end
   end
   found
 end

 end

This exits as soon as the second match is found, but you could have it run a method or something like that instead. You can also use throw/catch (note this is not about exceptions as with other languages using try/catch, it's meant to break out of deeply nested loops) to break out of the loop and go elsewhere. 

Regards,
Chris White
http://www.twitter.com/cwgem