From: Simon Strandgaard <neoneye@...>
Date: 2004-04-30T22:35:21+09:00
Subject: Re: Why is regexp "\Amax_repeats=(\d+)" not equal to "^max_repeats=([0-9]+)" ?

"Martin Elzen" <martinelzen@hotmail.com> wrote:
> I'm trying to learn how to program in Ruby, and yesterday I came across a 
> Regexp issue I can't figure out.  I want to parse a commandline argument of 
> the form: max_repeats=<integer>
> 
> After studying the 'pick-axe' book, I came up with the line:
> regexp = Regexp.new("\Amax_repeats=(\d+)")
> 
> but the above regexp fails to match with correct input.  When I changed that 
> line to the following:
> regexp = Regexp.new("^max_repeats=([0-9]+)")
> 
> it *does* match correctly with the proper input.
> 

Watch out about escaping inside double quoted strings..
observe the difference

irb(main):001:0> re = Regexp.new("\Ax")  
=> /Ax/
irb(main):002:0> re.match("xxx").to_a
=> []
irb(main):003:0> re = Regexp.new('\Ax')
=> /\Ax/
irb(main):004:0> re.match("xxx").to_a
=> ["x"]
irb(main):005:0>


Does this help you ?

--
Simon Strandgaard