PHP: Use associative arrays with preg_replace()

Question

In the documentation for preg_replace is says you can use indexed arrays to replace multiple strings. I would like to do this with associative arrays, but it seems to not work.

Does anyone know if this indeed does not work?

Answer 1

Do you want to do this on keys or the keys and values or just retain the keys and process the values? Whichever the case, array_combine(), array_keys() and array_values() can achieve this in combination.

On the keys:

$keys = array_keys($input);
$values = array_values($input);
$result = preg_replace($pattern, $replacement, $keys);
$output = array_combine($result, $values);

On the keys and values:

$keys = array_keys($input);
$values = array_values($input);
$newKeys = preg_replace($pattern, $replacement, $keys);
$newValues = preg_replace($pattern, $replacement, $values);
$output = array_combine($newKeys, $newValues);

On the values retaining keys:

$keys = array_keys($input);
$values = array_values($input);
$result = preg_replace($pattern, $replacement, $values);
$output = array_combine($keys, $result);

All of these assume a function something like:

function regex_replace(array $input, $pattern, $replacement) {
  ...
  return $output;
}

Answer 2

If I understand this correctly, what you want is:

$patterns = array_keys($input);
$replacements = array_values($input);
$output = preg_replace($patterns,$replacements,$string);