From: Robert Klemme <shortcutter@...>
Date: 2012-07-13T18:08:23+09:00
Subject: Re: how to check string is numeric or not

On Fri, Jul 13, 2012 at 10:19 AM, Lars Haugseth
<ruby-talk@larshaugseth.com> wrote:

> If o is allowed to be a Fixnum, you need to cast to string first:
>
>   /\A\d+\z/ === o.to_s

WTF?  (That's the first time I remember me writing this here.)

Let me get that straight: you want to convert something which you
*know* is an integer to a String to check whether it is an integer?

If o is allowed to be an integer type then you would better check that
directly (e.g. with Integer === o).  But it get's better:

irb(main):010:0> a=[1,1<<50,"1"]
=> [1, 1125899906842624, "1"]
irb(main):011:0> a.each {|x| y=Integer(x); printf "type %p converted
%p type %p\n", x.class, y, y.class}
type Fixnum converted 1 type Fixnum
type Bignum converted 1125899906842624 type Bignum
type String converted 1 type Fixnum
=> [1, 1125899906842624, "1"]

Cheers

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/