I don't see the relation between your link and that bit of the regex. However, that said, your skepticism of its utility seems justified. I tried to find a use for it, but I haven't been able to make \d{4,}? act any differently than \d{4}. It's either a useless construct, or a failure of my imagination in coming up with an appropriate test case.

Putting aside what YAPE::Regex::Explain says about it, when I looked at it originally, I thought "Yack! Perl is gonna bitch about that weird '?' character". I could think of a couple other interpretations, so I put together a bit of code to check 'em out:

my @tests = (               
    'First case',           
    '123456789second & third case',
);                          
                            
for my $t (@tests) {        
    print "\nchecking '$t'\n";                                        
+          
    if ($t=~/(\d{4,}?)(.*)/)   { print "A: $1, $2\n"; }
    if ($t=~/(\d{4,}?)(.*?)$/) { print "B: $1, $2\n"; }
}
[download]

The other interpretations I could think of were:

• An optional set of 4 or more digits, kind of like (?:\d{4,})?. If true, the first case would give us:

  A: , First case'
  [download]

• Exactly 4 digits, like \d{4}, giving us:

  checking '123456789second & third case'
  A: 1234, 56789second & third case
  B: 1234, 56789second & third case
  [download]

• 4 or more digits, with as few as possible, yielding:

  checking '123456789second & third case'
  A: 1234, 56789second & third case
  B: 123456789, second & third case
  [download]

On reading the ...explain() output, I thought that I could perhaps make the third case come about. But what I actually got was:

$ perl xxxyyyzzz.pl

checking 'First case'

checking '123456789second & third case'
A: 1234, 56789second & third case
B: 1234, 56789second & third case
[download]

So I'm thinking that my initial surprise was justified, even though it's syntactically correct.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.