On 11/17/06, Josselin <josselin / wanadoo.fr> wrote:
> After reading completely my Ruby book, I cannot find a function
> equivalent to the PHP  is_numeric? to test a String

There is no such function, although you can pretty readily use regexes
to do it...

It really is too bad that String.to_f does not throw an exception - or
at least return NaN - when the string is not a number.

> myString.is_numeric?   (check only digits and dot character)

A regex that matches the cases where String.to_f will find a value is
simple to write, and you can create String.numeric? like so:

class String
  def numeric?
    not ( self =~ /^[[:digit:]]+(\.[[:digit:]]+)?([eE][[:digit:]]+)?/ or
          self =~ /^\.[[:digit:]]+([eE][[:digit:]]+)?/ ).nil?
  end
end

-- 
_jsn