From: William Djaja Tjokroaminata <billtj@...>
Date: 2002-10-03T07:44:12+09:00
Subject: Re: Can soneone tell me what I'm doing wrong...

Hi Jeremy,

If you ever used C++, then you would have known the issue of deleting an
element while you are traversing the container using an iterator.

To make things straightforward, however, you should have used
"delete_if" instead of using "each" and "delete":

mp3DirName = ARGV[0]
mp3Dir = Dir.new(mp3DirName)
$fileNames = mp3Dir.entries
#this filters out things that aren't .mp3s
$fileNames.delete_if { |x| x !~ /.*mp3$/}         # this is modified
$fileNames.each { | fileName | print fileName + "\n" }

Regards,

Bill
============================================================================
Jeremy Gregorio <gunvalk@cox.net> wrote:
> I'm trying to write a little script to rename my mp3s I started with this:

> mp3DirName = ARGV[0]

> mp3Dir = Dir.new(mp3DirName)

> $fileNames = mp3Dir.entries

> #this filters out things that aren't .mp3s

> $fileNames.each { |x| if !(x =~ /.*mp3$/)
> 				

> 			$fileNames.delete(x)
> 			
> 		     end
> 		
> }#end each block

> $fileNames.each { | fileName | print fileName + "\n" }

> which should print the names of mp3s found the the directory given at 
> the command line. As near as I can tell the regex test is working right, 
> but $fileNames.delete(x) doesn't seem to be doing anything. I can do 
> $fileNames.delete("."); and that removes the entry "." from the list. I 
> haven't a clue why this doesn't just work, but I'm guessing/hoping it's 
> some idiosyncracy of ruby that I just don't know about. Thanks again guys :)

> Jeremy Gregorio
> gunvalk@cox.net