PHP String strip_tags() Function

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The PHP String strip_tags() function is used to remove a string from HTML and PHP tags. This function returns a string that has all NULL bytes, HTML, and PHP tags removed from the specified $str.

Syntax

Below is the syntax of the PHP String strip_tags() function −

string strip_tags ( string $string, array|string|null $allowed_tags = null )

Parameters

Here are the parameters of the strip_tags() function −

• $string − (Required) It is the indicates which string to examine.

• $allowed_tags − (Optional) It is used to determine the permitted tags. The tags will not be removed.

Return Value

The strip_tags() function returns the stripped string.

Exceptions/Errors

This function removes HTML comments and PHP tags. This cannot be used in $allowed_tags as it is already hardcoded. PHP 5.3.4 and later versions ignore self-closing XHTML elements. Strip_tags() does not check HTML.

PHP Version

First introduced in core PHP 4, the strip_tags() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

Here is the basic example of the PHP String strip_tags() function to remove all HTML and PHP tags from a simple string.

<?php
   // Input string with HTML tags.
   $input = "<p>Hello <b>World</b>!</p>";

   // Removes all HTML and PHP tags.
   $output = strip_tags($input);
   echo $output; 
?>

Output

Here is the outcome of the following code −

Hello World!

Example 2

This program demonstrates the use of strip_tags() function to show how to allow specific tags to remain in the string.

<?php
   // Input string with HTML tags.
   $input = "<p>Hello <b>Tutorialspoint</b>!</p>";

   // Removes all tags except the <b> tag.
   $output = strip_tags($input, "<b>");
   echo $output; 
?> 

Output

This will generate the below output −

Hello <b>Tutorialspoint</b>!

Example 3

Now the below code shows the use of an array to specify allowed tags in the strip_tags() function.

<?php
   // Input string with HTML tags.
   $input = "<div>Hello <b>World</b>! <i>Stay</i> Safe.</div>";

   // Specify an array of allowed tags.
   $allowed_tags = ["b", "i"];
   $output = strip_tags($input, $allowed_tags);
   echo $output; 
?> 

Output

This will create the below output −

Hello <b>World</b>! <i>Stay</i> Safe.

Example 4

In the following example, we are using the strip_tags() function to dynamically specifies allowed tags as per the user input.

<?php
   // Input string with HTML tags.
   $input = "<h1>Welcome</h1> <p>to the <i>World</i> of <b>PHP</b>!</p>";
   
   // User-specified allowed tags
   $user_allowed_tags = ["h1", "i"]; 
   $output = strip_tags($input, $user_allowed_tags);
   echo $output; 
?> 

Output

Following is the output of the above code −

<h1>Welcome</h1> to the <i>World</i> of PHP!