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run code in 300+ PHP versions simultaneously
<?php $str = 'This is <a href="http://foo.com">This is #foo</a>. simple #html-stuff text <a href="http://foobar.com#baz">#simple</a> <span class="simple">simple #simple text text</span>'; $str = preg_replace('/(?!<a[^<>]*>[^#]+)#(\b[-_\w]+\b)(?![^<]*<\/a>)/', '<a href="/tags/$1">#$1</a>', $str); echo $str;

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