From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-01-19T19:20:38+09:00
Subject: Re: string to int

On Tue, Jan 19, 2010 at 11:13 AM, Phillip Curry <philfo@gmail.com> wrote:
> Is there a nice way to convert a string to an integer if it is in fact an
> integer, and to return nil or even an error if it's not?  The method to_i
> returns 0 if the string is not an integer, which isn't hugely helpful, as I
> want to be able to distinguish between the integer 0 and non-integer
> strings.
> thanks
>

Try this:

irb(main):002:0> Integer("12")
=> 12
irb(main):003:0> Integer("fdfdf")
ArgumentError: invalid value for Integer: "fdfdf"
	from (irb):3:in `Integer'
	from (irb):3
	from :0
irb(main):005:0> Integer("12ijk")
ArgumentError: invalid value for Integer: "12ijk"
	from (irb):5:in `Integer'
	from (irb):5
	from :0
irb(main):006:0> "12ijk".to_i
=> 12

But check the last example: to_i would have returned 12 ignoring the
rest of the string, while Integer will raise an exception. Don't know
if this fits your criteria.

Jesus.