htmlentities
Convert all applicable characters to HTML entities.
htmlentities Function synopsis
htmlentities(
    string $string,
    int $flags = ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401,
    ?string $encoding = null,
    bool $double_encode = true
  ): string
Parameters
$string 
Typestring
The input string.
$flags 
OptionalTypeintDefault valueENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401
A bitmask of one or more of the following flags, which specify how to handle quotes,
invalid code unit sequences and the used document type. The default is
ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401.
$flags accepts one or a bitmask of the following constant values:
ENT_COMPATENT_QUOTESENT_NOQUOTESENT_IGNOREENT_SUBSTITUTEENT_DISALLOWEDENT_HTML401ENT_XML1ENT_XHTMLENT_HTML5
$encoding 
OptionalType?stringDefault valuenull
$double_encode 
OptionalTypeboolDefault valuetrue
When $double_encode is turned off PHP will not
encode existing html entities. The default is to convert everything.
Return value
Typestring
Returns the encoded string.
If the input $string contains an invalid code unit
sequence within the given $encoding an empty string
will be returned, unless either the ENT_IGNORE or
ENT_SUBSTITUTE flags are set.
Changes to the htmlentities Function 
PHP 8.1
- Parameter default value changed for position #2 (
$flags):ENT_COMPATtoENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401 
  htmlentities(
      string $string,
-     int $flags = ENT_COMPAT,
+     int $flags = ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401,
      ?string $encoding = null,
      bool $double_encode = true
    ): string  PHP 8.0
- Return type added: 
string - Parameter type added for parameter #1 (
$string):string - Parameter name of parameter #2 changed: 
$quote_styleto$flags - Parameter type added for parameter #2 (
$flags):int - Parameter default value added for position #2 (
$flags):ENT_COMPAT - Parameter type added for parameter #3 (
$encoding):?string - Parameter default value added for position #3 (
$encoding):null - Parameter type added for parameter #4 (
$double_encode):bool - Parameter default value added for position #4 (
$double_encode):true 
  htmlentities(
-     $string,
+     string $string,
-     $quote_style,
+     int $flags = ENT_COMPAT,
-     $encoding,
+     ?string $encoding = null,
-     $double_encode
+     bool $double_encode = true
-   )
+   ): string  PHP 7.0
- Parameter name of parameter #3 changed: 
$charsetto$encoding 
  htmlentities(
      $string,
      $quote_style,
-     $charset,
+     $encoding,
      $double_encode
    )  htmlentities Function Availability
htmlentities Function Availability| PHP Version | Availability | 
|---|---|
| PHP 8.6Future Release | Yes | 
| PHP 8.5Upcoming Release | Yes | 
| PHP 8.4Supported (Latest) | Yes | 
| PHP 8.3Supported | Yes | 
| PHP 8.2Security-Fixes Only | Yes | 
| PHP 8.1Security-Fixes Only | Yes | 
| PHP 8.0Unsupported | Yes | 
| PHP 7.4Unsupported | Yes | 
| PHP 7.3Unsupported | Yes | 
| PHP 7.2Unsupported | Yes | 
| PHP 7.1Unsupported | Yes | 
| PHP 7.0Unsupported | Yes | 
| PHP 5.6Unsupported | Yes | 
| PHP 5.5Unsupported | Yes | 
| PHP 5.4Unsupported | Yes | 
| PHP 5.3Unsupported | Yes |