From: Raul Parolari <raulparolari@...>
Date: 2007-11-23T09:54:51+09:00
Subject: Re: Checking whether a string is a number in disguise?


Stefano Crocco wrote:
> Alle gioved狸 22 novembre 2007...
> In this case, you can either use Kernel#Float, which returns str.to_f 
> .. or try to craft a regexp which only matches strings containing
>  numbers. 
> For example, the (untested) regexp
> 
> /[+-]?\d+(.\d+)?(e[+-]?\d+)?/

Two small additions:
a) the 'dot' should be literally a dot (else it matches any character)
b) the boundaries to the whole expresssion are needed (else "ab23.35de" 
would be
validated).

So, the regexp should be something like:

 /^ [+-]? \d+ (?: [.]\d+)? (?: e[+-]? \d+)? $ /x

(If capture of components is desired, parenthesis should enclose all 
components, and the ?: removed).

Raul
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