How can I reuse the key value of the search parameter in the replace parameter in str_replace()?

Question

What would be the syntax to reuse the key value of the search parameter in the replace parameter, for example

$key = array($value1, $value2, …);
echo str_replace($key, "<span class='key'>$key</span>", $content);

The above will return an Array rather than a single array item.

Answer 1

You can also use preg_replace_callback. Str replace doesn't accept arguments in the replacement string.

$key = array($value1, $value2, …);
$regex = addslashes(implode('|', $key));
$content = preg_replace_callback(
  "/$regex/",
  function ($matches) {
    return '<span class="key">'.$matches[0].'</span>';
  },
  $content
);

bitWorking has a better answer though if you can make each value in the array it's own regular expression.

Answer 2

Use preg_replace

$key = array('/a/', '/b/');
echo preg_replace($key, '<span class="key">$0</span>', 'a b');