Convert surrounding underscores into tags

Question

How would I convert uderscores surrounding words and sentences from a chunk of text into italic tags with PHP. Thanks in advance.

So -

This is _just_ a test string for the _purposes of this example_.

Would become -

This is <i>just</i> a test string for the <i>purposes of this example</i>.

Answer 1

$content = "This is _just_ a test string for the _purposes of this example_.";

preg_match_all("|_(.*)_|U",$content,$rows);

foreach($rows[0] as $key=>$row) {
    $content = str_replace($row, "<i>".$rows[1][$key]."</i>", $content);
}
echo $content;

This is just a test string for the purposes of this example.

Answer 2

Basically with regular expressions. Note that this might have undesired effects, if underscores appear elsewhere, e.g. in pre-existing HTML tags and URLs. If so, you'll have to experiment with \b as well.

preg_replace('/_(\w[^<>\n]+?\w)_/', '<i>$1</i>', $text);

Or, use a ready-made Wiki parser, if that's what you need.

Answer 3

1. Visit http://daringfireball.net/projects/markdown/ to learn Markdown syntax.
2. Visit http://michelf.com/projects/php-markdown/ to download and install a PHP version.
3. Call $html = Markdown("_text_"); from your PHP.