in reply to need help with a Regex

Peamasii,
I am terrible at regexes myself, but it seems like an anchored character class with an ungreedy quantifier would do the trick. 
/^[\d?]?$/

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Cheers - L~R

After reading dragonchild's reply, I have to agree - reading perldoc perlre, checking the Categorized Questions and Answers, and Super Searching are always good places to start. It is like the saying goes Give a man a fire and he stays warm for the day, set a man on fire and he is warm for the rest of his life give a man a fish and he is full for a day, teach a man to fish and he never goes hungry.

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Re^2: need help with a Regex
by Dietz (Curate) on Oct 06, 2004 at 15:32 UTC
    L~R, you are right with using anchors to limit the scope.
    But your solution would only match a single digit instead of a number (not what the OP wanted).

    One solution would be (not documented as of dragonchild's post):
    /^(\d+|\?)?$/

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    ++ for the right approach
    Monkish Greetings,
    Dietz
[reply]
[d/l]
      Dietz,
      But your solution would only match a single digit instead of a number (not what the OP wanted). emphasis mine

      Well see here is the quandry. You have interpreted it one way and I have another. Peamasii didn't define what exactly s/he meant by number. It could mean a single digit as I used, it could mean an integer which you described (which will match 0004 and miss -4 btw), or it could mean any number (pun intended) of things. For instance: 

      use Scalar::Util 'looks_like_number';
if ( looks_like_number( $foo ) && $foo =~ /^\??$/ ) {...}

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      It is probably as common a mistake to assume what you are thinking is universally understood when asking questions as it is for the person that is answering to assume they know what you mean. I think we both fall into the latter category this time.

      Cheers - L~R

[reply]
[d/l]
        Well, numbers fall into so many possible formats that it's impossible to catch them all. I'm going to assume that any integer or decimal format is allowed, and write the following: 
        foreach (<DATA>) { print $_ if $_ =~ /^(\?|-?\d*\.?\d+)?$/; }
__DATA__

?
3
3.3
.3
-3
-3.3
-.3
 ?
3-3
-

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[reply]
[d/l]
        L~R, you are right again.
        Didn't see it the way you described, especially when it comes to numbers with a minus before.

        I was just recognizing the single digit match. And I was hesitating to post anyways (as of dragonchild's post above)

        And I really didn't mean to offend you, I have great respect for you - as I have for most other monks here.

        Respect, Dietz
[reply]
      You probably don't need the capturing parens. I'd write it as 
      /^(?:\d*|\?)$/

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      where the empty string is just a zero digit number, but that's just me.
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[d/l]

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