Question: how to remove only this type of special chars ░▒▓█► from a string in php
I use this `preg_replace('/[\x00-\x1F\x80-\xC0]/u', '',$string);` 

but i want to allow special char like à,â, ', ", for french language

Answer: 
You can use unicode character classes like `\p{Latin}` for latin script, `\p{Sc}` for currency, `\p{P}` (or shorter `\pP`) for punctuation characters:

```
$str = preg_replace('/[^0-9\p{Latin}\pP\p{Sc}@\s]+/u', '', $str);

```

You can find the different unicode character classes available in PCRE [here](http://pcre.org/original/pcre.txt). (search the sentence: *"The following general category property codes are supported"*)
So, you want use the code point of UTF-8 but you want use the character encoding scheme of [ISO 8859-15](http://en.wikipedia.org/wiki/ISO/IEC_8859-15). I think you can do it converting the string twice:

```
$text = iconv("ISO-8859-15", "UTF-8", iconv("UTF-8", "ISO-8859-15//IGNORE", $text));
echo $text;

```