From: Rick DeNatale <rick.denatale@...>
Date: 2010-07-12T02:05:15+09:00
Subject: Re: Basic Question: How do you check to see if gets is a number?

On Sun, Jul 11, 2010 at 12:34 PM, Adam Bourg <adam.bourg89@gmail.com> wrote:
> if ( age.to_f.to_s == true )

This will NEVER happen.

age.to_f converts the string to a float. If the string isn't valid it
returns 0.0.

age.to_f.to_s will ALWAYS be a string, and will never == true

>  monthsold = age.to_i * months.to_i
>  puts 'You are ' + monthsold.to_s + ' months old'
> else
>

Now I'm not sure whether or not you really want to accept an age as a
float, or just an integer, but you need to do something else to
validate the string.

One way would be to use a regular expression, e.g. something like

if age =~ /^d+$/  # for an integer
or
if age =~/^d+(|\.\d*)$/ # for a float

These are fairly strict in what they'll accept, you might want
slightly different regular expressions, particularly if you really
want a float.

Or use either Kernel#Integer or Kernel#Float which raise an error if
they don't like the string:

float_age = Float(age) rescue nil
if float_age
#....

HTH

-- 
Rick DeNatale

Blog: http://talklikeaduck.denhaven2.com/
Github: http://github.com/rubyredrick
Twitter: @RickDeNatale
WWR: http://www.workingwithrails.com/person/9021-rick-denatale
LinkedIn: http://www.linkedin.com/in/rickdenatale