[php] How to remove html special chars?

I am creating a RSS feed file for my application in which I want to remove HTML tags, which is done by strip_tags. But strip_tags is not removing HTML special code chars:

  & © 

etc.

Please tell me any function which I can use to remove these special code chars from my string.

The function I used to perform the task, joining the upgrade made by schnaader is:

    mysql_real_escape_string(
        preg_replace_callback("/&#?[a-z0-9]+;/i", function($m) { 
            return mb_convert_encoding($m[1], "UTF-8", "HTML-ENTITIES"); 
        }, strip_tags($row['cuerpo'])))

This function removes every html tag and html symbol, converted in UTF-8 ready to save in MySQL

In addition to the good answers above, PHP also has a built-in filter function that is quite useful: filter-var.

To remove HMTL characters, use:

$cleanString = filter_var($dirtyString, FILTER_SANITIZE_STRING);

More info:

1. function.filter-var
2. filter_sanitize_string

<?php
function strip_only($str, $tags, $stripContent = false) {
    $content = '';
    if(!is_array($tags)) {
        $tags = (strpos($str, '>') !== false
                 ? explode('>', str_replace('<', '', $tags))
                 : array($tags));
        if(end($tags) == '') array_pop($tags);
    }
    foreach($tags as $tag) {
        if ($stripContent)
             $content = '(.+</'.$tag.'[^>]*>|)';
         $str = preg_replace('#</?'.$tag.'[^>]*>'.$content.'#is', '', $str);
    }
    return $str;
}

$str = '<font color="red">red</font> text';
$tags = 'font';
$a = strip_only($str, $tags); // red text
$b = strip_only($str, $tags, true); // text
?> 

This might work well to remove special characters.

$modifiedString = preg_replace("/[^a-zA-Z0-9_.-\s]/", "", $content); 

try this

<?php
$str = "\x8F!!!";

// Outputs an empty string
echo htmlentities($str, ENT_QUOTES, "UTF-8");

// Outputs "!!!"
echo htmlentities($str, ENT_QUOTES | ENT_IGNORE, "UTF-8");
?>

A plain vanilla strings way to do it without engaging the preg regex engine:

function remEntities($str) {
  if(substr_count($str, '&') && substr_count($str, ';')) {
    // Find amper
    $amp_pos = strpos($str, '&');
    //Find the ;
    $semi_pos = strpos($str, ';');
    // Only if the ; is after the &
    if($semi_pos > $amp_pos) {
      //is a HTML entity, try to remove
      $tmp = substr($str, 0, $amp_pos);
      $tmp = $tmp. substr($str, $semi_pos + 1, strlen($str));
      $str = $tmp;
      //Has another entity in it?
      if(substr_count($str, '&') && substr_count($str, ';'))
        $str = remEntities($tmp);
    }
  }
  return $str;
}

If you want to convert the HTML special characters and not just remove them as well as strip things down and prepare for plain text this was the solution that worked for me...

function htmlToPlainText($str){
    $str = str_replace(' ', ' ', $str);
    $str = html_entity_decode($str, ENT_QUOTES | ENT_COMPAT , 'UTF-8');
    $str = html_entity_decode($str, ENT_HTML5, 'UTF-8');
    $str = html_entity_decode($str);
    $str = htmlspecialchars_decode($str);
    $str = strip_tags($str);

    return $str;
}

$string = '<p>this is (&nbsp;) a test</p>
<div>Yes this is! &amp; does it get "processed"? </div>'

htmlToPlainText($string);
// "this is ( ) a test. Yes this is! & does it get processed?"`

html_entity_decode w/ ENT_QUOTES | ENT_XML1 converts things like ' htmlspecialchars_decode converts things like & html_entity_decode converts things like '< and strip_tags removes any HTML tags left over.

EDIT - Added str_replace(' ', ' ', $str); and several other html_entity_decode() as continued testing has shown a need for them.

$string = "äácé";

$convert = Array(
        'ä'=>'a',
        'Ä'=>'A',
        'á'=>'a',
        'Á'=>'A',
        'à'=>'a',
        'À'=>'A',
        'ã'=>'a',
        'Ã'=>'A',
        'â'=>'a',
        'Â'=>'A',
        'c'=>'c',
        'C'=>'C',
        'c'=>'c',
        'C'=>'C',
        'd'=>'d',
        'D'=>'D',
        'e'=>'e',
        'E'=>'E',
        'é'=>'e',
        'É'=>'E',
        'ë'=>'e',
    );

$string = strtr($string , $convert );

echo $string; //aace

If you are working in WordPress and are like me and simply need to check for an empty field (and there are a copious amount of random html entities in what seems like a blank string) then take a look at:

sanitize_title_with_dashes( string $title, string $raw_title = '', string $context = 'display' )

Link to wordpress function page

For people not working on WordPress, I found this function REALLY useful to create my own sanitizer, take a look at the full code and it's really in depth!

You can try htmlspecialchars_decode($string). It works for me.

http://www.w3schools.com/php/func_string_htmlspecialchars_decode.asp

It looks like what you really want is:

function xmlEntities($string) {
    $translationTable = get_html_translation_table(HTML_ENTITIES, ENT_QUOTES);

    foreach ($translationTable as $char => $entity) {
        $from[] = $entity;
        $to[] = '&#'.ord($char).';';
    }
    return str_replace($from, $to, $string);
}

It replaces the named-entities with their number-equivalent.

You may want take a look at htmlentities() and html_entity_decode() here

$orig = "I'll \"walk\" the <b>dog</b> now";

$a = htmlentities($orig);

$b = html_entity_decode($a);

echo $a; // I'll &quot;walk&quot; the &lt;b&gt;dog&lt;/b&gt; now

echo $b; // I'll "walk" the <b>dog</b> now

What I have done was to use: html_entity_decode, then use strip_tags to removed them.

Use html_entity_decode to convert HTML entities.

You'll need to set charset to make it work correctly.