note 110511 deleted from function.preg-replace by crell

Note Submitter: cincodenada at gmail dot dot dot com ---- There seems to be some confusion over how greediness works. For those familiar with Regular Expressions in other languages, particularly Perl: it works like you would expect, and as documented. Greedy by default, un-greedy if you follow a quantifier with a question mark. There is a PHP/PCRE-specific U pattern modifier that flips the greediness, so that quantifiers are by default un-greedy, and become greedy if you follow the quantifier with a question mark: http://www.php.net/manual/en/reference.pcre.pattern.modifiers.php To make things clear, a series of examples: <?php $preview = "a bunch of stuff <code>this that</code> and more stuff <code>with a second code block</code> then extra at the end"; $preview_default = preg_replace('/<code>(.*)<\/code>/is', "<code class=\"prettyprint\">$1</code>", $preview); $preview_manually_ungreedy = preg_replace('/<code>(.*?)<\/code>/is', "<code class=\"prettyprint\">$1</code>", $preview); $preview_U_default = preg_replace('/<code>(.*)<\/code>/isU', "<code class=\"prettyprint\">$1</code>", $preview); $preview_U_manually_greedy = preg_replace('/<code>(.*?)<\/code>/isU', "<code class=\"prettyprint\">$1</code>", $preview); echo "Default, no ?: $preview_default\n"; echo "Default, with ?: $preview_manually_ungreedy\n"; echo "U flag, no ?: $preview_U_default\n"; echo "U flag, with ?: $preview_U_manually_greedy\n"; ?> Results in this: Default, no ?: a bunch of stuff <code class="prettyprint">this that</code> and more stuff <code>with a second code block</code> then extra at the end Default, with ?: a bunch of stuff <code class="prettyprint">this that</code> and more stuff <code class="prettyprint">with a second code block</code> then extra at the end U flag, no ?: a bunch of stuff <code class="prettyprint">this that</code> and more stuff <code class="prettyprint">with a second code block</code> then extra at the end U flag, with ?: a bunch of stuff <code class="prettyprint">this that</code> and more stuff <code>with a second code block</code> then extra at the end As expected: greedy by default, ? inverts it to ungreedy. With the U flag, un-greedy by default, ? makes it greedy.