From: Gavin Sinclair <gsinclair@...>
Date: 2002-09-24T15:43:41+09:00
Subject: Re: Checking hash key's and values, with case insensitivity


----- Original Message -----
From: <dblack@candle.superlink.net>


> Hi --
>
> On Tue, 24 Sep 2002, Gavin Sinclair wrote:
>
> > ----- Original Message -----
> > From: "Yukihiro Matsumoto" <matz@ruby-lang.org>
> >
> > >
> > > |How can I check hash keys and values without case sensitivity?
> > > |Specifically I'm referring to the hash ".has_key?" and ".has_value?"
> > > |methods.  I believe these are case sensitive by default.
> > >
> > > Why not simply
> > >
> > >  h.key?(k.upcase)
> > >  h.value?(v.upcase)
> > >
> > > matz.
> >
> > This has got to be the best solution, as it takes account of the important
fact
> > that noone else has yet mentioned: Hash keys are not necessarily Strings.
>
> What if the key you used is lowercase?  like this:
>
>   irb(main):002:0> h = {"a" => 1}
>   {"a"=>1}
>   irb(main):003:0> k = "a"
>   "a"
>   irb(main):004:0> h.key?(k)
>   true
>   irb(main):005:0> h.key?(k.upcase)
>   false
>

I think Matz intended that the keys get case-neutralised upon entry into the
hash.  Naturally, that stuffs you if you input both "Key" and "kEy" into the
hash, but as someone pointed out, if genuine case-insensitive retrieval is what
you want, then hash is not what you need.

May I suggest a binary tree or similar structure, in case the original poster
is still interested?

Gavin