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    <p>edg is correct, but the original code is unnecessarily obtuse. In most cases, <code>$#foo</code> is a red flag that the code could be written more simply using <code>scalar @foo</code>.</p> <pre><code>return (undef) unless ($#ret &gt;= 0); </code></pre> <p><code>unless foo &gt;= bar</code> is difficult to puzzle out. First, turn it into a positive statement.</p> <pre><code>return (undef) if ($#ret &lt; 0); </code></pre> <p>When is $#ret &lt; 0? When it's -1. A $#ret of -1 is an array of length 0. So the above can be written much more simply as...</p> <pre><code>return (undef) if scalar @ret &lt;= 0; </code></pre> <p>But you can't have a negative length array, so...</p> <pre><code>return (undef) if scalar @ret == 0; </code></pre> <p>And == is in scalar context, so that "scalar" is redundant...</p> <pre><code>return (undef) if @ret == 0; </code></pre> <p>But that's just a wordy way of saying "if <code>@ret</code> is false".</p> <pre><code>return (undef) if !@ret; </code></pre> <p>Which I think for simple statement modifiers is better expressed with unless.</p> <pre><code>return (undef) unless @ret; </code></pre> <p>Isn't that easier to follow?</p> <p>As a final side-note, <code>return undef</code> is discouraged because it does the wrong thing in list context. You get back a list containing one undef element, which is true. Instead, just use a blank return which returns undef in scalar context and an empty list in list context.</p> <pre><code>return unless @ret; </code></pre>
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    1. POWhat does $#array mean in Perl?
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    1. USSchwern
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    1. COAnd one place where $#foo isn't a red flag would be in an array slice... my @five_to_end = @foo[ 5 .. $#foo ];
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    2. COMighty fine simplification!
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      1. USJustin R.
    3. CORe: `return undef` being discouraged. In some cases, you do want to return an explicit `undef` even in list context. It depends on how the function is usually used. It's not that you shouldn't use `return undef`, it's just that you shouldn't use it without thinking "why am I using `return undef` here?" If you have a good answer, then go ahead and do it.
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