PHP htmlspecialchars() Function

The htmlspecialchars() function converts some predefined characters to HTML entities.

The predefined characters are:

  • & (ampersand) becomes &
  • " (double quote) becomes "
  • ' (single quote) becomes '
  • < (less than) becomes &lt;
  • > (greater than) becomes &gt;

To convert special HTML entities back to characters, use the htmlspecialchars_decode() function.

If the input string passed to this function and the final document share the same character set, this function is sufficient to prepare input for inclusion in most contexts of an HTML document. If, however, the input can represent characters that are not coded in the final document character set and you wish to retain those characters (as numeric or named entities), both this function and htmlentities() (which only encodes substrings that have named entity equivalents) may be insufficient. You may have to use mb_encode_numericentity() instead.

Example -

Example #1 htmlspecialchars() example

ParameterDescription
stringRequired. Specifies the string to convert
flagsOptional. Specifies how to handle quotes, invalid encoding and the used document type.
The available quote styles are:
  • ENT_COMPAT - Default. Encodes only double quotes
  • ENT_QUOTES - Encodes double and single quotes
  • ENT_NOQUOTES - Does not encode any quotes
  • Invalid encoding:
  • ENT_IGNORE - Ignores invalid encoding instead of having the function return an empty string. Should be avoided, as it may have security implications.
  • ENT_SUBSTITUTE - Replaces invalid encoding for a specified character set with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD; instead of returning an empty string.
  • ENT_DISALLOWED - Replaces code points that are invalid in the specified doctype with a Unicode Replacement Character U+FFFD (UTF-8) or &#FFFD;
  • Additional flags for specifying the used doctype:
  • ENT_HTML401 - Default. Handle code as HTML 4.01
  • ENT_HTML5 - Handle code as HTML 5
  • ENT_XML1 - Handle code as XML 1
  • ENT_XHTML - Handle code as XHTML
  • character-setOptional. A string that specifies which character-set to use.
    Allowed values are:
  • UTF-8 - Default. ASCII compatible multi-byte 8-bit Unicode
  • ISO-8859-1 - Western European
  • ISO-8859-15 - Western European (adds the Euro sign + French and Finnish letters missing in ISO-8859-1)
  • cp866 - DOS-specific Cyrillic charset
  • cp1251 - Windows-specific Cyrillic charset
  • cp1252 - Windows specific charset for Western European
  • KOI8-R - Russian
  • BIG5 - Traditional Chinese, mainly used in Taiwan
  • GB2312 - Simplified Chinese, national standard character set
  • BIG5-HKSCS - Big5 with Hong Kong extensions
  • Shift_JIS - Japanese
  • MacRoman - Character-set that was used by Mac OS
  • double_encodeOptional. A boolean value that specifies whether to encode existing html entities or not.
  • TRUE - Default. Will convert everything
  • FALSE - Will not encode existing html entities
  • The converted 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.