Question

In this pattern:

$pattern = '/(\s*)@(if|foreach)(\s*\(.*\))/';

How can I replace every # with $ on (\s*(.*))

This will be used afterwards:

preg_replace($pattern, '$1<?php $2$3: ?>', $value);

Answer 1

You are looking for preg_replace_callback.

There you can define an anonymous function that returns the replacement, where you would be able to perform your additional task on group 3 and then build the replacement as you need.

From the example in the second link

<?php
echo preg_replace_callback('~-([a-z])~', function ($match) {
    return strtoupper($match[1]);
}, 'hello-world');
// outputs helloWorld
?>

You can see that you can access the group 3 like this: $match[3]