htmlspecialchars

Convert special characters to HTML entities

Syntax

htmlspecialchars(
    string $string,
    int $flags = ENT_QUOTES | ENT_SUBSTITUTE | ENT_HTML401,
    ?string $encoding = null,
    bool $double_encode = true
): string

Parameters

string

The string being converted.

Character Replacement
& (ampersand) &
" (double quote) ", unless ENT_NOQUOTES is set
' (single quote) ' (for ENT_HTML401) or ' (for ENT_XML1, ENT_XHTML or ENT_HTML5), but only when ENT_QUOTES is set
< (less than) &lt;
> (greater than) &gt;
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_COMPAT | 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 &#xFFFD; (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 &#xFFFD; (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

An optional argument defining the encoding used when converting characters.

If omitted, encoding defaults to the value of the default_charset configuration option.

Although this argument is technically optional, you are highly encouraged to specify the correct value for your code if the default_charset configuration option may be set incorrectly for the given input.

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.

Charset Aliases Description
ISO-8859-1 ISO8859-1 Western European, Latin-1.
ISO-8859-5 ISO8859-5 Little used cyrillic charset (Latin/Cyrillic).
ISO-8859-15 ISO8859-15 Western European, Latin-9. Adds the Euro sign, French and Finnish letters missing in Latin-1 (ISO-8859-1).
UTF-8 ASCII compatible multi-byte 8-bit Unicode.
cp866 ibm866, 866 DOS-specific Cyrillic charset.
cp1251 Windows-1251, win-1251, 1251 Windows-specific Cyrillic charset.
cp1252 Windows-1252, 1252 Windows specific charset for Western European.
KOI8-R koi8-ru, koi8r Russian
BIG5 950 Traditional Chinese, mainly used in Taiwan.
GB2312 936 Simplified Chinese, national standard character set.
BIG5-HKSCS Big5 with Hong Kong extensions, Traditional Chinese.
Shift_JIS SJIS, SJIS-win, cp932, 932 Japanese
EUC-JP EUCJP, eucJP-win Japanese
MacRoman Charset that was used by Mac OS.
'' An empty string activates detection from script encoding (Zend multibyte), default_charset and current locale (see nl_langinfo() and setlocale()), in this order. Not recommended.

Note: Any other character sets are not recognized. The default encoding will be used instead and a warning will be emitted.

double_encode

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

Return

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.

Examples

1 · string

<?

$string = "& | &amp;" . PHP_EOL
. "\" | &quot;" . PHP_EOL
. "' | &#039;" . PHP_EOL
. "< | &lt;" . PHP_EOL
. "> | &gt;" . PHP_EOL
. "über | &uuml;ber" . PHP_EOL
. "<b>bold</b> | &lt;b&gt;bold&lt;/b&gt;";

$return = htmlspecialchars($string);

echo $return;

?>
&amp; | &amp;amp;
&quot; | &amp;quot;
&#039; | &amp;#039;
&lt; | &amp;lt;
&gt; | &amp;gt;
über | &amp;uuml;ber
&lt;b&gt;bold&lt;/b&gt; | &amp;lt;b&amp;gt;bold&amp;lt;/b&amp;gt;

2 · flags

<?

$string = "& | &amp;" . PHP_EOL
. "\" | &quot;" . PHP_EOL
. "' | &#039;" . PHP_EOL
. "< | &lt;" . PHP_EOL
. "> | &gt;" . PHP_EOL
. "über | &uuml;ber" . PHP_EOL
. "<b>bold</b> | &lt;b&gt;bold&lt;/b&gt;";
$flags = ENT_QUOTES;

$return = htmlspecialchars($string, $flags);

echo $return;

?>
&amp; | &amp;amp;
&quot; | &amp;quot;
&#039; | &amp;#039;
&lt; | &amp;lt;
&gt; | &amp;gt;
über | &amp;uuml;ber
&lt;b&gt;bold&lt;/b&gt; | &amp;lt;b&amp;gt;bold&amp;lt;/b&amp;gt;

3 · encoding

<?

$string = "& | &amp;" . PHP_EOL
. "\" | &quot;" . PHP_EOL
. "' | &#039;" . PHP_EOL
. "< | &lt;" . PHP_EOL
. "> | &gt;" . PHP_EOL
. "über | &uuml;ber" . PHP_EOL
. "<b>bold</b> | &lt;b&gt;bold&lt;/b&gt;";
$flags = ENT_QUOTES;
$encoding = "UTF-8";

$return = htmlspecialchars($string, $flags, $encoding);

echo $return;

?>
&amp; | &amp;amp;
&quot; | &amp;quot;
&#039; | &amp;#039;
&lt; | &amp;lt;
&gt; | &amp;gt;
über | &amp;uuml;ber
&lt;b&gt;bold&lt;/b&gt; | &amp;lt;b&amp;gt;bold&amp;lt;/b&amp;gt;

4 · double_encode

<?

$string = "& | &amp;" . PHP_EOL
. "\" | &quot;" . PHP_EOL
. "' | &#039;" . PHP_EOL
. "< | &lt;" . PHP_EOL
. "> | &gt;" . PHP_EOL
. "über | &uuml;ber" . PHP_EOL
. "<b>bold</b> | &lt;b&gt;bold&lt;/b&gt;";
$flags = ENT_QUOTES;
$encoding = "UTF-8";
$double_encode = false;

$return = htmlspecialchars($string, $flags, $encoding, $double_encode);

echo $return;

?>
&amp; | &amp;
&quot; | &quot;
&#039; | &#039;
&lt; | &lt;
&gt; | &gt;
über | &uuml;ber
&lt;b&gt;bold&lt;/b&gt; | &lt;b&gt;bold&lt;/b&gt;

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