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copied!<p>Perls <code>grep</code> function selects/filters all elements from a list that match a certain condition. In your case, you selected all elements that match the regex <code>/Number/</code> from the <code>@input_file</code> array.</p> <p>To select the non-whitespace string after <code>Number</code> use this Regex:</p> <pre><code>my $regex = qr{ Number # Match the literal string 'Number' \s+ # match any number of whitespace characters ([^\s;]+) # Capture the following non-spaces-or-semicolons into $1 # using a negated character class }x; # use /x modifier to allow whitespaces in pattern # for better formatting </code></pre> <p>My suggestion would be to loop directly over the input file handle:</p> <pre><code>while(defined(my $line = <$input>)) { $line =~ /$regex/; print "Found: $1" if length $1; # skip if nothing was found } </code></pre> <p>If you have to use an array, a <code>foreach</code>-loop would be preferable:</p> <pre><code>foreach my $line (@input_lines) { $line =~ /$regex/; print "Found: $1" if length $1; # skip if nothing was found } </code></pre> <p>If you don't want to print your matches directly but to store them in an array, <code>push</code> the values into the array inside your loop (both work) or use the <code>map</code> function. The map function replaces each input element by the value of the specified operation:</p> <pre><code>my @result = map {/$regex/; length $1 ? $1 : ()} @input_file; </code></pre> <p>or</p> <pre><code>my @result = map {/$regex/; length $1 ? $1 : ()} <$input>; </code></pre> <p>Inside the <code>map</code> block, we match the regex against the current array element. If we have a match, we return <code>$1</code>, else we return an <em>empty list</em>. This gets flattened into invisibility so we don't create an entry in <code>@result</code>. This is different form returning <code>undef</code>, what would create an undef element in your array.</p>

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