[PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8]
mb_detect_encoding — Detect character encoding
Description
mb_detect_encoding[string $string, array|string|null $encodings =
null, bool $strict = false]: string|false
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.
Parameters
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.
Return Values
The detected character encoding, or false if the string is not valid in any of the listed encodings.
Examples
Example #1 mb_detect_encoding[] example
Example #2 Effect of strict parameter
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:
- "Ä¢" [U+00C4 LATIN CAPITAL LETTER A WITH DIAERESIS followed by U+00A2 CENT SIGN] encoded in any of ISO-8859-1, ISO-8859-15, or Windows-1252
- "ФЂ" [U+0424 CYRILLIC CAPITAL LETTER EF followed by U+0402 CYRILLIC CAPITAL LETTER DJE] encoded in ISO-8859-5
- "Ģ" [U+0122 LATIN CAPITAL LETTER G WITH CEDILLA] encoded in UTF-8
Example #3 Effect of order when multiple encodings match
The above example will output:
string[5] "UTF-8" string[10] "ISO-8859-1" string[10] "ISO-8859-5"
Gerg Tisza ¶
11 years ago
If you try to use mb_detect_encoding to detect whether a string is valid UTF-8, use the strict mode, it is pretty worthless otherwise.
Chrigu ¶
17 years ago
If you need to distinguish between UTF-8 and ISO-8859-1 encoding, list UTF-8 first in your encoding_list:
mb_detect_encoding[$string, 'UTF-8, ISO-8859-1'];
if you list ISO-8859-1 first, mb_detect_encoding[] will always return ISO-8859-1.
chris AT w3style.co DOT uk ¶
16 years ago
Based upon that snippet below using preg_match[] I needed something faster and less specific. That function works and is brilliant but it scans the entire strings and checks that it conforms to UTF-8. I wanted something purely to check if a string contains UTF-8 characters so that I could switch character encoding from iso-8859-1 to utf-8.
I modified the pattern to only look for non-ascii multibyte sequences in the UTF-8 range and also to stop once it finds at least one multibytes string. This is quite a lot faster.
rl at itfigures dot nl ¶
15 years ago
I used Chris's function "detectUTF8" to detect the need from conversion from utf8 to 8859-1, which works fine. I did have a problem with the following iconv-conversion.
The problem is that the iconv-conversion to 8859-1 [with //TRANSLIT] replaces the euro-sign with EUR, although it is common practice that \x80 is used as the euro-sign in the 8859-1 charset.
I could not use 8859-15 since that mangled some other characters, so I added 2 str_replace's:
if[detectUTF8[$str]]{
$str=str_replace["\xE2\x82\xAC","€",$str];
$str=iconv["UTF-8","ISO-8859-1//TRANSLIT",$str];
$str=str_replace["€","\x80",$str];
}
If html-output is needed the last line is not necessary [and even unwanted].
nat3738 at gmail dot com ¶
13 years ago
A simple way to detect UTF-8/16/32 of file by its BOM [not work with string or file without BOM]
php-note-2005 at ryandesign dot com ¶
17 years ago
Much simpler UTF-8-ness checker using a regular expression created by the W3C:
hmdker at gmail dot com ¶
14 years ago
Function to detect UTF-8, when mb_detect_encoding is not available it may be useful.
recentUser at example dot com ¶
4 years ago
In my environment [PHP 7.1.12],
"mb_detect_encoding[]" doesn't work
where "mb_detect_order[]" is not set appropriately.
To enable "mb_detect_encoding[]" to work in such a case,
simply put "mb_detect_order['...']"
before "mb_detect_encoding[]" in your script file.
Both
"ini_set['mbstring.language', '...'];"
and
"ini_set['mbstring.detect_order', '...'];"
DON'T work in script files for this purpose
whereas setting them in PHP.INI file may work.
garbage at iglou dot eu ¶
5 years ago
For detect UTF-8, you can use:
if [preg_match['!!u', $str]] { echo 'utf-8'; }
- Norihiori
bmrkbyet at web dot de ¶
9 years ago
a] if the FUNCTION mb_detect_encoding is not available:
### mb_detect_encoding ... iconv ###
### mb_convert_encoding ... iconv ###
b] if the FUNCTION mb_convert_encoding is not available:
emoebel at web dot de ¶
8 years ago
if the function " mb_detect_encoding" does not exist ...
... try:
example / usage of: mb_detect_encoding[]
$txtstr = str_to_utf8[$txtstr];
d_maksimov ¶
5 months ago
It was helpful for my exec[...] call. When it returned cp866 or cp1251:
try {
$line = iconv['CP866', 'CP1251', $line];
} catch[Exception $e] {
}
return iconv['CP1251', 'UTF-8', $line];
telemach ¶
17 years ago
beware : even if you need to distinguish between UTF-8 and ISO-8859-1, and you the following detection order [as chrigu suggests]
mb_detect_encoding['accentu?e' , 'UTF-8, ISO-8859-1']
returns ISO-8859-1, while
mb_detect_encoding['accentu?' , 'UTF-8, ISO-8859-1']
returns UTF-8
bottom line : an ending '?' [and probably other accentuated chars] mislead mb_detect_encoding
maarten ¶
17 years ago
Sometimes mb_detect_string is not what you need. When using pdflib for example you want to VERIFY the correctness of utf-8. mb_detect_encoding reports some iso-8859-1 encoded text as utf-8.
To verify utf 8 use the following:
//
// utf8 encoding validation developed based on Wikipedia entry at:
// //en.wikipedia.org/wiki/UTF-8
//
// Implemented as a recursive descent parser based on a simple state machine
// copyright 2005 Maarten Meijer
//
// This cries out for a C-implementation to be included in PHP core
//
function valid_1byte[$char] {
if[!is_int[$char]] return false;
return [$char & 0x80] == 0x00;
}
function valid_2byte[$char] {
if[!is_int[$char]] return false;
return [$char & 0xE0] == 0xC0;
}
function valid_3byte[$char] {
if[!is_int[$char]] return false;
return [$char & 0xF0] == 0xE0;
}
function valid_4byte[$char] {
if[!is_int[$char]] return false;
return [$char & 0xF8] == 0xF0;
}
function valid_nextbyte[$char] {
if[!is_int[$char]] return false;
return [$char & 0xC0] == 0x80;
}
function valid_utf8[$string] {
$len = strlen[$string];
$i = 0;
while[ $i < $len ] {
$char = ord[substr[$string, $i++, 1]];
if[valid_1byte[$char]] { // continue
continue;
} else if[valid_2byte[$char]] { // check 1 byte
if[!valid_nextbyte[ord[substr[$string, $i++, 1]]]]
return false;
} else if[valid_3byte[$char]] { // check 2 bytes
if[!valid_nextbyte[ord[substr[$string, $i++, 1]]]]
return false;
if[!valid_nextbyte[ord[substr[$string, $i++, 1]]]]
return false;
} else if[valid_4byte[$char]] { // check 3 bytes
if[!valid_nextbyte[ord[substr[$string, $i++, 1]]]]
return false;
if[!valid_nextbyte[ord[substr[$string, $i++, 1]]]]
return false;
if[!valid_nextbyte[ord[substr[$string, $i++, 1]]]]
return false;
} // goto next char
}
return true; // done
}
for a drawing of the statemachine see: //www.xs4all.nl/~mjmeijer/unicode.png and //www.xs4all.nl/~mjmeijer/unicode2.png
yaqy at qq dot com ¶
14 years ago
Anonymous ¶
8 years ago
// -----------------------------------------------------------
if[!function_exists['mb_detect_encoding']] {
function mb_detect_encoding[$string, $enc=null, $ret=true] {
$out=$enc;
static $list = array['utf-8', 'iso-8859-1', 'iso-8859-15', 'windows-1251'];
foreach [$list as $item] {
$sample = iconv[$item, $item, $string];
if [md5[$sample] == md5[$string]] { $out = [$ret !== false] ? true : $item; }
}
return $out;
}
}
// -----------------------------------------------------------
matthijs at ischen dot nl ¶
13 years ago
I seriously underestimated the importance of setlocale...
Produces the following:
Array
[
[0] => mais coisas a pensar sobre diario ou dois!
[1] => plus de choses a penser a journalier ou a deux !
[2] => ?mas cosas a pensar en diario o dos!
[3] => piu cose da pensare circa giornaliere o due!
[4] => flere ting aa tenke paa hver dag eller to!
[5] => Dalsi veci, premyslet o kazdy den nebo dva!
[6] => mehr ueber Spass spaet schoenen
[7] => me vone gjate fun bukur
[8] => toebb mint szorakozas keso csodalatos kenyer
]
whereas
produces:
Array
[
[0] => mais coisas a pensar sobre di?rio ou dois!
[1] => plus de choses ? penser ? journalier ou ? deux !
[2] => ?m?s cosas a pensar en diario o dos!
[3] => pi? cose da pensare circa giornaliere o due!
[4] => flere ting ? tenke p? hver dag eller to!
[5] => Dal?? v?c?, p?em??let o ka?d? den nebo dva!
[6] => mehr ?ber Spass sp?t sch?nen
[7] => m? von? gjat? fun bukur
[8] => t?bb mint sz?rakoz?s k?s? csod?latos keny?r
]
This might be of interest when trying to convert utf-8 strings into ASCII suitable for URL's, and such. this was never obvious for me since I've used locales for us and nl.
jaaks at playtech dot com ¶
17 years ago
Last example for verifying UTF-8 has one little bug. If 10xxxxxx byte occurs alone i.e. not in multibyte char, then it is accepted although it is against UTF-8 rules. Make following replacement to repair it.
Replace
} // goto next char
with
} else {
return false; // 10xxxxxx occuring alone
} // goto next char
lexonight at yahoo dot com ¶
5 years ago
seems to work
prgss at bk dot ru ¶
13 years ago
Another light way to detect character encoding:
sunggsun ¶
16 years ago
from PHPDIG
function isUTF8[$str] {
if [$str === mb_convert_encoding[mb_convert_encoding[$str, "UTF-32", "UTF-8"], "UTF-8", "UTF-32"]] {
return true;
} else {
return false;
}
}