From: Peter Vandenabeele <peter@...>
Date: 2012-02-09T18:05:02+09:00
Subject: Re: How to catch first occurence of [a-z]

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On Thu, Feb 9, 2012 at 6:07 AM, Mario Trento <dainova@yahoo.com> wrote:

> Hi,
>
> Yes, I'm in learning mode and trying to see how I can change very first
> occurrence of alpha char in string (or list), in my example first char
> in string could be \s or \t, so I need to check for this.
> It's multi line string, so I broke up it in list elements = line, and
> now thinking how to process it.
> What string function I can use?
>
>
> list = multi_linestring.split(/\n/)
>   ##then iterate thru each line { |ll| ......????}
>
> Thanks all
>

Writing an example is shorter than a long explanation. As
your learning experience, try to understand in detail how/why
this works ...

$ irb
1.9.3p0 :001 > "   \t  \t  first  line \nsecond line".split(/\n/).each do
|line|
1.9.3p0 :002 >     line.sub!(/[a-zA-Z]/, '*')
1.9.3p0 :003?>   end
 => ["   \t  \t  *irst  line ", "*econd line"]

Hints:
* check the difference between sub , sub! , gsub , gsub!
* check character classes in regular expressions

HTH,

Peter

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Peter Vandenabeele
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