Test if a regular expression is a valid one in PHP

Question

I am writing a form validation class and wish to include regular expressions in the validation. Therefore, the regex provided isn\'t guaranteed to be valid.

How can

Answer 1

You shouldn't be using @ to silence all errors because it also silences fatal errors.

function isRegularExpression($string) {
  set_error_handler(function() {}, E_WARNING);
  $isRegularExpression = preg_match($string, "") !== FALSE;
  restore_error_handler();
  return isRegularExpression;
}

This only silences warnings for the preg_match call.