remove in php any character but not symbols and letters

Question

how I can use str_ireplace or other functions to remove any characters but not letters,numbers or symbols that are commonly used in HTML as : " ' ; : . - + = ... etc. I also wants to remove /n, white spaces, tabs and other.

I need that text, comes from doing ("textContent"). innerHTML in IE10 and Chrome, which a php variable are the same size, regardless of which browser do it.Therefore I need the same encoding in both texts and characters that are rare or different are removed.

I try this, but it dont work for me:

        $textForMatch=iconv(mb_detect_encoding($text, mb_detect_order(), true), "UTF-8", $text);
        $textoForMatc = str_replace(array('\s', "\n", "\t", "\r"), '', $textoForMatch);

$text contains the result of the function ("textContent"). innerHTML, I want to delete characters as é³..

Answer 1

The easiest option is to simply use preg_replace with a whitelist. Ie use a pattern listing the things you want to keep, and replace anything not in that list:

$input = 'The quick brown 123 fox said "�é³". Man was I surprised';
$stripped = preg_replace('/[^-\w:";:+=\.\']/', '', $input);
$output = 'Thequickbrownfoxsaid"".ManwasIsurprised';

regex explanation

/       - start regex
[^      - Begin inverted character class, match NON-matching characters
-       - litteral character
\w      - Match word characters. Equivalent to A-Za-z0-9_
:";:+=  - litteral characters
\.      - escaped period (because a dot has meaning in a regex)
\'      - escaped quote (because the string is in single quotes)
]       - end character class
/       - end of regex

This will therefore remove anything that isn't words, numbers or the specific characters listed in the regex.