From: Golda Bence <gbence@...>
Date: 2007-11-06T22:08:45+09:00
Subject: Re: Start of string?

Hi!

Take a look at Regexp class:

	http://www.ruby-doc.org/core/classes/Regexp.html

...after that your starts_with? method should be similar to this one:

class String
  def starts_with?(a_string)
    self =~ Regexp.new('^%s' % [ a_string ])
  end
end

a = "long string"
a.starts_with?("long")          # => 0
a.starts_with?("not soo long")  # => nil

!note: in ruby 0 (Fixnum) means true in a condition, so does ""
(String), but nil (NilClass) means false.

Cheers, Bence

Jari Williamsson wrote:
> What't the most elegant way to find a substring match at the very start
> of a string?
> 
> Currently I'm using this approach:
> a = "long string"
> key = "long"
> if a[0, key.length] == key then
> 
> ...while this might look ok, it doesn't look so good with constant strings:
> if a[0, 4] == "long" then
> or
> if a[0, "long".length] == "long" then
> 
> I guess what I'm looking for is something like:
> if a.startswith("long") then
> 
> Is there any such solution?
> 
> 
> Best regards,
> 
> Jari Williamsson