From: 7stud -- <bbxx789_05ss@...>
Date: 2007-11-02T14:34:00+09:00
Subject: Re: Can't get my regexp to work to test if numerical

7stud -- wrote:
> Feng Tien wrote:
>> alright, this seems easy enough.
>> 
>> Building a Bank class, deposits must be floating, so if it has any
>> letters, it will tell the user it needs numbers
>> 
>> 
>>          if amount == /^[0-9]$/
>>          deposit_to_acct(amount,current_account)
>>          puts 'You have deposited ' + amount.to_s
>> 
>>           else
>>           puts 'Must be a number, alphabet bank is next door to your
>> right'
>> 
>>         end
> 
> 1) The pattern /^[0-9]$/ matches one digit.
> 

That's incorrect.  The pattern matches: the start of the line, followed 
by one digit, followed by the end of the line.   So the regex won't 
match a digit in a line containing two digits:

regex = /^[0-9]$/

line = '8'
match_obj = regex.match(line)
p match_obj.to_a

line = '12'
match_obj = regex.match(line)
p match_obj.to_a

--output:--
["8"]
[]

You certainly don't have to use regex's to convert a string to a float 
(or an int).  Look at String#to_f and Kernel.Float.

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