How to replace html tag with other tags using preg-match?

Question

I have a string like the following.

<label>value1<label>:value<br>
<label>value2<label>:value<br>
<label>value3<label>:value<br>

and i need to arrange this as following

 <li><label>value1<label><span>value</span><li>

i have tried for this last 2 days, but no luck.Any help?

Answer 1

This really isn't something you should do with regex. You might be able to fudge together a solution that works provided it makes a lot of assumptions about the content it's parsing, but it will always be fragile and liable to break should that content deviate from the expected by any significant degree.

A better bet is using PHP's DOM family of classes. I'm not really at liberty to write the code for you (and that's not what SO is for anyway), but I can give you a pointer regarding the steps you need to follow.

1. Locate text nodes that follow a label and precede a BR (XPath may be useful here)
2. Put the text node into a span.
3. Insert the span into the DOM after the label
4. Remove the BR.
5. wrap label and span in an li

Answer 2

If, for the sake of regex, you should use it then follow as below :

$string = <<<TOK
<label>value1<label>:value<br>
<label>value2<label>:value<br>
<label>value3<label>:value<br>
TOK;
preg_match_all('/<label>(.*?)<label>\:(.*?)<br>/s', $string, $matches);
print_r($matches);
/*
Array
(
    [0] => Array
        (
            [0] => value1:value
            [1] => value2:value
            [2] => value3:value
        )
    [1] => Array
        (
            [0] => value1
            [1] => value2
            [2] => value3
        )

    [2] => Array
        (
            [0] => value
            [1] => value
            [2] => value
        )
)
*/
$content = "";
foreach($matches as $key => $match)
{
    $content.= "<li><label>{$matches[1][$key]}<label><span>{$matches[2][$key]}</span><li>\n";
}
echo($content);
/*
Output:
    <li><label>value1<label><span>value</span><li>
    <li><label>value2<label><span>value</span><li>
    <li><label>value3<label><span>value</span><li>
*/