I would like to sanitize a string in to a URL so this is what I basically need:
Eg.
This, is the URL! must return
this-is-the-url 
function slug($z){ $z = strtolower($z); $z = preg_replace('/[^a-z0-9 -]+/', '', $z); $z = str_replace(' ', '-', $z); return trim($z, '-'); } 
First strip unwanted characters
$new_string = preg_replace("/[^a-zA-Z0-9\s]/", "", $string); Then changes spaces for unserscores
$url = preg_replace('/\s/', '-', $new_string); Finally encode it ready for use
$new_url = urlencode($url); 
_ is an underscore, - is a hyphen. Also using urlencode on such a string doesn't change anything. You're also forgetting hypen in the first regex and \s is not equivalent to space character.The OP is not explicitly describing all of the attributes of a slug, but this is what I am gathering from the intent.
My interpretation of a perfect, valid, condensed slug aligns with this post: https://wordpress.stackexchange.com/questions/149191/slug-formatting-acceptable-characters#:~:text=However%2C%20we%20can%20summarise%20the,or%20end%20with%20a%20hyphen.
I find none of the earlier posted answers to achieve this consistently (and I'm not even stretching the scope of the question to include multi-byte characters).
I recommend the following one-liner which doesn't bother declaring single-use variables:
return trim(preg_replace('/[^a-z0-9]+/', '-', strtolower($string)), '-'); Not shown in my demo link, here is an attempt to better handle multibyte strings, though it doesn't quite accommodate as many scenarios as Casimir's answer.
return trim(preg_replace('/[^a-z0-9]+/', '-', strtolower(iconv('utf-8', 'ascii//translit', $string))), '-'); I have also prepared a demonstration which highlights what I consider to be inaccuracies in the other answers. (Demo)
'This, is - - the URL!' input 'this-is-the-url' expected 'this-is-----the-url' SilentGhost 'this-is-the-url' mario 'This-is---the-URL' Rooneyl 'This-is-the-URL' AbhishekGoel 'This, is - - the URL!' HelloHack 'This, is - - the URL!' DenisMatafonov 'This,-is-----the-URL!' AdeelRazaAzeemi 'this-is-the-url' mickmackusa --- 'Mork & Mindy' input 'mork-mindy' expected 'mork--mindy' SilentGhost 'mork-mindy' mario 'Mork--Mindy' Rooneyl 'Mork-Mindy' AbhishekGoel 'Mork & Mindy' HelloHack 'Mork & Mindy' DenisMatafonov 'Mork-&-Mindy' AdeelRazaAzeemi 'mork-mindy' mickmackusa --- 'What the_underscore ?!?' input 'what-the-underscore' expected 'what-theunderscore' SilentGhost 'what-the_underscore' mario 'What-theunderscore-' Rooneyl 'What-theunderscore-' AbhishekGoel 'What the_underscore ?!?' HelloHack 'What the_underscore ?!?' DenisMatafonov 'What-the_underscore-?!?' AdeelRazaAzeemi 'what-the-underscore' mickmackusa This will do it in a Unix shell (I just tried it on my MacOS):
$ tr -cs A-Za-z '-' < infile.txt > outfile.txt I got the idea from a blog post on More Shell, Less Egg
Try This
function clean($string) { $string = str_replace(' ', '-', $string); // Replaces all spaces with hyphens. $string = preg_replace('/[^A-Za-z0-9\-]/', '', $string); // Removes special chars. return preg_replace('/-+/', '-', $string); // Replaces multiple hyphens with single one. } Usage:
echo clean('a|"bc!@£de^&$f g'); Will output: abcdef-g
Using intl transliterator is a good option because with it you can easily handle complicated cases with a single set of rules. I added custom rules to illustrate how it can be flexible and how you can keep a maximum of meaningful informations. Feel free to remove them and to add your own rules.
$strings = [ 'This, is - - the URL!', 'Holmes & Yoyo', 'L’Œil de démon', 'How to win 1000€?', '€, $ ＆ other currency symbols', 'Und die Katze fraß alle mäuse.', 'Белите рози на София', 'പോണ്ടിച്ചേരി സൂര്യനു കീഴിൽ', ]; $rules = <<<'RULES' # Transliteration :: Any-Latin ; :: Latin-Ascii ; # examples of custom replacements '&' > ' and ' ; [^0-9][01]? { € > ' euro' ; € > ' euros' ; [^0-9][01]? { '$' > ' dollar' ; '$' > ' dollars' ; :: Null ; # slugify [^[:alnum:]&[:ascii:]]+ > '-' ; :: Lower ; # trim [$] { '-' > &Remove() ; '-' } [$] > &Remove() ; RULES; $tsl = Transliterator::createFromRules($rules, Transliterator::FORWARD); $results = array_map(fn($s) => $tsl->transliterate($s), $strings); print_r($results); Unfortunately, the PHP manual is totally empty about ICU transformations but you can find informations about them here.
All previous asnwers deal with url, but in case some one will need to sanitize string for login (e.g.) and keep it as text, here is you go:
function sanitizeText($str) { $withSpecCharacters = htmlspecialchars($str); $splitted_str = str_split($str); $result = ''; foreach ($splitted_str as $letter){ if (strpos($withSpecCharacters, $letter) !== false) { $result .= $letter; } } return $result; } echo sanitizeText('ОРРииыфвсси ajvnsakjvnHB "&nvsp;\n" <script>alert()</script>'); //ОРРииыфвсси ajvnsakjvnHB &nvsp;\n scriptalert()/script //No injections possible, all info at max keeped 
function isolate($data) { $data = trim($data); $data = stripslashes($data); $data = htmlspecialchars($data); return $data; } 
You should use the slugify package and not reinvent the wheel ;)
The following will replace spaces with dashes.
$str = str_replace(' ', '-', $str); Then the following statement will remove everything except alphanumeric characters and dashed. (didn't have spaces because in previous step we had replaced them with dashes.
// Char representation 0 - 9 A- Z a- z - $str = preg_replace('/[^\x30-\x39\x41-\x5A\x61-\x7A\x2D]/', '', $str); Which is equivalent to
$str = preg_replace('/[^0-9A-Za-z-]+/', '', $str); FYI: To remove all special characters from a string use
$str = preg_replace('/[^\x20-\x7E]/', '', $str); \x20 is hexadecimal for space that is start of Acsii charecter and \x7E is tilde. As accordingly to wikipedia https://en.wikipedia.org/wiki/ASCII#Printable_characters
FYI: look into the Hex Column for the interval 20-7E
Printable characters Codes 20hex to 7Ehex, known as the printable characters, represent letters, digits, punctuation marks, and a few miscellaneous symbols. There are 95 printable characters in total.
