(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
mb_detect_encoding — Detect character encoding
$string, array|string|null $encodings = null, bool $strict = false): string|false
Detects the most likely character encoding for string string
from an ordered list of candidates.
Automatic detection of the intended character encoding can never be entirely reliable; without some additional information, it is similar to decoding an encrypted string without the key. It is always preferable to use an indication of character encoding stored or transmitted with the data, such as a "Content-Type" HTTP header.
This function is most useful with multibyte encodings, where not all sequences of bytes form a valid string. If the input string contains such a sequence, that encoding will be rejected, and the next encoding checked.
stringThe string being inspected.
encodingsA list of character encodings to try, in order. The list may be specified as an array of strings, or a single string separated by commas.
If encodings is omitted or null,
the current detect_order (set with the
mbstring.detect_order configuration option, or mb_detect_order()
function) will be used.
strict
Controls the behaviour when string
is not valid in any of the listed encodings.
If strict is set to false, the closest matching
encoding will be returned; if strict is set to true,
false will be returned.
The default value for strict can be set
with the
mbstring.strict_detection configuration option.
The detected character encoding, or false if the string is not valid
in any of the listed encodings.
| Version | Description |
|---|---|
| 8.2.0 |
mb_detect_encoding() will no longer return
the following non text encodings:
"Base64", "QPrint",
"UUencode", "HTML entities",
"7 bit" and "8 bit".
|
Example #1 mb_detect_encoding() example
<?php
// Detect character encoding with current detect_order
echo mb_detect_encoding($str);
// "auto" is expanded according to mbstring.language
echo mb_detect_encoding($str, "auto");
// Specify "encodings" parameter by list separated by comma
echo mb_detect_encoding($str, "JIS, eucjp-win, sjis-win");
// Use array to specify "encodings" parameter
$encodings = [
"ASCII",
"JIS",
"EUC-JP"
];
echo mb_detect_encoding($str, $encodings);
?>
Example #2 Effect of strict parameter
<?php
// 'áéóú' encoded in ISO-8859-1
$str = "\xE1\xE9\xF3\xFA";
// The string is not valid ASCII or UTF-8, but UTF-8 is considered a closer match
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8'], false));
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8'], true));
// If a valid encoding is found, the strict parameter does not change the result
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8', 'ISO-8859-1'], false));
var_dump(mb_detect_encoding($str, ['ASCII', 'UTF-8', 'ISO-8859-1'], true));
?>The above example will output:
string(5) "UTF-8" bool(false) string(10) "ISO-8859-1" string(10) "ISO-8859-1"
In some cases, the same sequence of bytes may form a valid string in multiple character encodings, and it is impossible to know which interpretation was intended. For instance, among many others, the byte sequence "\xC4\xA2" could be:
Example #3 Effect of order when multiple encodings match
<?php
$str = "\xC4\xA2";
// The string is valid in all three encodings, so the first one listed will be returned
var_dump(mb_detect_encoding($str, ['UTF-8', 'ISO-8859-1', 'ISO-8859-5']));
var_dump(mb_detect_encoding($str, ['ISO-8859-1', 'ISO-8859-5', 'UTF-8']));
var_dump(mb_detect_encoding($str, ['ISO-8859-5', 'UTF-8', 'ISO-8859-1']));
?>The above example will output:
string(5) "UTF-8" string(10) "ISO-8859-1" string(10) "ISO-8859-5"