PHP preg_replace special characters

Question

I am wanting to replace all non letter and number characters i.e. /&%#$ etc with an underscore (_) and replace all ' (single quotes) with ""blank (so no underscore).

So "There wouldn't be any" (ignore the double quotes) would become "There_wouldnt_be_any".

I am useless at reg expressions hence the post.

Cheers

Answer 1

If you by writing "non letters and numbers" exclude more than [A-Za-z0-9] (ie. considering letters like åäö to be letters to) and want to be able to accurately handle UTF-8 strings \p{L} and \p{N} will be of aid.

1. \p{N} will match any "Number"
2. \p{L} will match any "Letter Character", which includes
   • Lower case letter
   • Modifier letter
   • Other letter
   • Title case letter
   • Upper case letter

Documentation PHP: Unicode Character Properties

---

$data = "Thäre!wouldn't%bé#äny";

$new_data = str_replace  ("'", "", $data);
$new_data = preg_replace ('/[^\p{L}\p{N}]/u', '_', $new_data);

var_dump (
  $new_data
);

output

string(23) "Thäre_wouldnt_bé_äny"

Answer 2

do this in two steps:

1. replace not letter characters with this regex:

   [\/\&%#\$]

2. replace quotes with this regex:

   [\"\']

and use preg_replace:

$stringWithoutNonLetterCharacters = preg_replace("/[\/\&%#\$]/", "_", $yourString);
$stringWithQuotesReplacedWithSpaces = preg_replace("/[\"\']/", " ", $stringWithoutNonLetterCharacters);