As far as I understand the debugger, both expressions are evaluated in list context.
The first expression simply returns 1 for success and I assume 0 an empty list for failure; so it's a single boolean result in list context.
The second expression has capturing parantheses, which (in list context) produces a list of captured results. As your (p)* could not be matched, there is no captured value for (p), so it returns a list with one element: undef.
That's my attempt to explain it. I am sure there are others who can explain it more detailed and accurately and even show some insight into the internals ...
DB<4> x "24-06" =~ /\d+-\d+/
0 1
DB<5> x "24-06" =~ /\d+-\d+failure/
empty array
edit:
- fixed assumption upon failed regex match, added code example, some rephrasing
-
Are you posting in the right place? Check out Where do I post X? to know for sure.
-
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big>
<blockquote> <br /> <dd>
<dl> <dt> <em> <font>
<h1> <h2> <h3> <h4>
<h5> <h6> <hr /> <i>
<li> <nbsp> <ol> <p>
<small> <strike> <strong>
<sub> <sup> <table>
<td> <th> <tr> <tt>
<u> <ul>
-
Snippets of code should be wrapped in
<code> tags not
<pre> tags. In fact, <pre>
tags should generally be avoided. If they must
be used, extreme care should be
taken to ensure that their contents do not
have long lines (<70 chars), in order to prevent
horizontal scrolling (and possible janitor
intervention).
-
Want more info? How to link
or How to display code and escape characters
are good places to start.
|