htmlspecialchars

Description

Certain characters have special significance in HTML, and should be represented by HTML entities if they are to preserve their meanings. This function returns a string with these conversions made. If you require all input substrings that have associated named entities to be translated, use htmlentities() instead.

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.

Parameters

string

The string being converted.

flags

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.

Constant Name	Description
ENT_COMPAT	Will convert double-quotes and leave single-quotes alone.
ENT_QUOTES	Will convert both double and single quotes.
ENT_NOQUOTES	Will leave both double and single quotes unconverted.
ENT_IGNORE	Silently discard invalid code unit sequences instead of returning an empty string. Using this flag is discouraged as it may have security implications.
ENT_SUBSTITUTE	Replace invalid code unit sequences with a Unicode Replacement Character U+FFFD (UTF-8) or � (otherwise) instead of returning an empty string.
ENT_DISALLOWED	Replace invalid code points for the given document type with a Unicode Replacement Character U+FFFD (UTF-8) or � (otherwise) instead of leaving them as is. This may be useful, for instance, to ensure the well-formedness of XML documents with embedded external content.
ENT_HTML401	Handle code as HTML 4.01.
ENT_XML1	Handle code as XML 1.
ENT_XHTML	Handle code as XHTML.
ENT_HTML5	Handle code as HTML 5.

encoding

Encoding

For the purposes of this function, the encodings ISO-8859-1, ISO-8859-15, UTF-8, cp866, cp1251, cp1252, and KOI8-R are effectively equivalent, provided the string itself is valid for the encoding, as the characters affected by htmlspecialchars() occupy the same positions in all of these encodings.

Charsets

double_encode

When double_encode is turned off PHP will not encode existing html entities, the default is to convert everything.

Return Values

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.

Changelog

Examples

htmlspecialchars() example

<?php
$new = htmlspecialchars("<a href='test'>Test</a>", ENT_QUOTES);
echo $new; // &lt;a href=&#039;test&#039;&gt;Test&lt;/a&gt;
?>

ENT_IGNORE and ENT_SUBSTITUTE with invalid UTF-8 sequences

<?php
// "\x80" is not a valid UTF-8 byte sequence.
$input = "atta\x80ck";

// ENT_IGNORE silently drops the invalid byte - output: "attack"
echo bin2hex(htmlspecialchars($input, ENT_QUOTES | ENT_IGNORE, 'UTF-8')), "\n";
// 61747461636b

// ENT_SUBSTITUTE replaces the invalid byte with U+FFFD - output: "atta" + replacement char + "ck"
echo bin2hex(htmlspecialchars($input, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8')), "\n";
// 61747461efbfbd636b
?>

Notes

See Also

• get_html_translation_table()
• htmlspecialchars_decode()
• strip_tags()
• htmlentities()
• nl2br()