Yeah you're right,
> match = 'Today is Feb 23rd, 2003'.match(/Feb 23(rd)??/)
> match[0] #=> "Feb 23"
> match[1] #=> nil
I expected:
> match = 'Today is Feb 23rd, 2003'.match(/Feb 23(rd)?/) # ? is greedy here
> match[0] #=> "Feb 23rd"
> match[1] #=> nil
But what I got in ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32] is:
> match[0] #=> "Feb 23rd"
> match[1] #=> 'rd'
The behavior of '?' being greedy is correct since it matched "Feb
23rd" which is stored in match[0] . But should match[1] not be nil?
The regular expression does not match "rd" alone.
thanks
On Sun, Oct 19, 2008 at 11:34 PM, Frederick Cheung
<[EMAIL PROTECTED]> wrote:
>
>
> On 19 Oct 2008, at 15:01, mars wrote:
>
>>
>> Hi!
>>
>> I couldn't understand the behavior of this code:
>>
>> match = 'Today is Feb 23rd, 2003'.match(/Feb 23(rd)?/)
>> a = match.to_a
>> puts a.size # 2
>> puts a.join(",") # Feb 23rd,rd
>> puts a[0] # Feb 23rd
>> puts a[1] # rd
>>
>> In my understanding, /Feb 23(rd)?/ is equivalent to /Feb 23|Feb
>> 23rd/ . So, match should not include 'rd'.
>
> ? + and * are greedy, ie they always try to match as much of the
> string as possible so rd is part of the match.
> If you want a non greedy quantifier you need to add ? to it, for example
> match = 'Today is Feb 23rd, 2003'.match(/Feb 23(rd)??/)
> match[0] #=> "Feb 23"
>
> Fred
>
> >
>
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