PHP 5.5.17 is available

mb_detect_encoding

(PHP 4 >= 4.0.6, PHP 5)

mb_detect_encodingDetect character encoding

Description

string mb_detect_encoding ( string $str [, mixed $encoding_list = mb_detect_order() [, bool $strict = false ]] )

Detects character encoding in string str.

Parameters

str

The string being detected.

encoding_list

encoding_list is list of character encoding. Encoding order may be specified by array or comma separated list string.

If encoding_list is omitted, detect_order is used.

strict

strict specifies whether to use the strict encoding detection or not. Default is FALSE.

Return Values

The detected character encoding or FALSE if the encoding cannot be detected from the given string.

Examples

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 encoding_list character encoding by comma separated list */
echo mb_detect_encoding($str"JIS, eucjp-win, sjis-win");

/* Use array to specify encoding_list  */
$ary[] = "ASCII";
$ary[] = "JIS";
$ary[] = "EUC-JP";
echo 
mb_detect_encoding($str$ary);
?>

See Also

add a note add a note

User Contributed Notes 19 notes

up
13
chris AT w3style.co DOT uk
8 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.

<?php

function detectUTF8($string)
{
        return
preg_match('%(?:
        [\xC2-\xDF][\x80-\xBF]        # non-overlong 2-byte
        |\xE0[\xA0-\xBF][\x80-\xBF]               # excluding overlongs
        |[\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}      # straight 3-byte
        |\xED[\x80-\x9F][\x80-\xBF]               # excluding surrogates
        |\xF0[\x90-\xBF][\x80-\xBF]{2}    # planes 1-3
        |[\xF1-\xF3][\x80-\xBF]{3}                  # planes 4-15
        |\xF4[\x80-\x8F][\x80-\xBF]{2}    # plane 16
        )+%xs'
, $string);
}

?>
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8
Gerg Tisza
3 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.

<?php
    $str
= 'áéóú'; // ISO-8859-1
   
mb_detect_encoding($str, 'UTF-8'); // 'UTF-8'
   
mb_detect_encoding($str, 'UTF-8', true); // false
?>
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5
nat3738 at gmail dot com
5 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
// Unicode BOM is U+FEFF, but after encoded, it will look like this.
define ('UTF32_BIG_ENDIAN_BOM'   , chr(0x00) . chr(0x00) . chr(0xFE) . chr(0xFF));
define ('UTF32_LITTLE_ENDIAN_BOM', chr(0xFF) . chr(0xFE) . chr(0x00) . chr(0x00));
define ('UTF16_BIG_ENDIAN_BOM'   , chr(0xFE) . chr(0xFF));
define ('UTF16_LITTLE_ENDIAN_BOM', chr(0xFF) . chr(0xFE));
define ('UTF8_BOM'               , chr(0xEF) . chr(0xBB) . chr(0xBF));

function
detect_utf_encoding($filename) {

   
$text = file_get_contents($filename);
   
$first2 = substr($text, 0, 2);
   
$first3 = substr($text, 0, 3);
   
$first4 = substr($text, 0, 3);
   
    if (
$first3 == UTF8_BOM) return 'UTF-8';
    elseif (
$first4 == UTF32_BIG_ENDIAN_BOM) return 'UTF-32BE';
    elseif (
$first4 == UTF32_LITTLE_ENDIAN_BOM) return 'UTF-32LE';
    elseif (
$first2 == UTF16_BIG_ENDIAN_BOM) return 'UTF-16BE';
    elseif (
$first2 == UTF16_LITTLE_ENDIAN_BOM) return 'UTF-16LE';
}
?>
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3
emoebel at web dot de
8 months ago
if the  function " mb_detect_encoding" does not exist  ...

... try:

<?php
// ----------------------------------------------------
if ( !function_exists('mb_detect_encoding') ) {

// ----------------------------------------------------------------
function mb_detect_encoding ($string, $enc=null, $ret=null) {
      
        static
$enclist = array(
           
'UTF-8', 'ASCII',
           
'ISO-8859-1', 'ISO-8859-2', 'ISO-8859-3', 'ISO-8859-4', 'ISO-8859-5',
           
'ISO-8859-6', 'ISO-8859-7', 'ISO-8859-8', 'ISO-8859-9', 'ISO-8859-10',
           
'ISO-8859-13', 'ISO-8859-14', 'ISO-8859-15', 'ISO-8859-16',
           
'Windows-1251', 'Windows-1252', 'Windows-1254',
            );
       
       
$result = false;
       
        foreach (
$enclist as $item) {
           
$sample = iconv($item, $item, $string);
            if (
md5($sample) == md5($string)) {
                if (
$ret === NULL) { $result = $item; } else { $result = true; }
                break;
            }
        }
       
    return
$result;
}
// ----------------------------------------------------------------

}
// ----------------------------------------------------
?>

example / usage of: mb_detect_encoding()

<?php
// ------------------------------------------------------
function str_to_utf8 ($str) {
   
    if (
mb_detect_encoding($str, 'UTF-8', true) === false) {
   
$str = utf8_encode($str);
    }

    return
$str;
}
// ------------------------------------------------------
?>

$txtstr = str_to_utf8($txtstr);
up
5
Anonymous
11 months 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;
}

}

// -----------------------------------------------------------
up
3
bmrkbyet at web dot de
1 year ago
a) if the FUNCTION mb_detect_encoding is not available:

### mb_detect_encoding ... iconv ###

<?php
// -------------------------------------------

if(!function_exists('mb_detect_encoding')) {
function
mb_detect_encoding($string, $enc=null) {
   
    static
$list = array('utf-8', 'iso-8859-1', 'windows-1251');
   
    foreach (
$list as $item) {
       
$sample = iconv($item, $item, $string);
        if (
md5($sample) == md5($string)) {
            if (
$enc == $item) { return true; }    else { return $item; }
        }
    }
    return
null;
}
}

// -------------------------------------------
?>

b) if the FUNCTION mb_convert_encoding is not available:

### mb_convert_encoding ... iconv ###

<?php
// -------------------------------------------

if(!function_exists('mb_convert_encoding')) {
function
mb_convert_encoding($string, $target_encoding, $source_encoding) {
   
$string = iconv($source_encoding, $target_encoding, $string);
    return
$string;
}
}

// -------------------------------------------
?>
up
2
dennis at nikolaenko dot ru
5 years ago
Beware of bug to detect Russian encodings
http://bugs.php.net/bug.php?id=38138
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1
jaaks at playtech dot com
9 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
up
2
yaqy at qq dot com
6 years ago
<?php
/*
*QQ: 290359552
* conver to Utf8 if $str is not equals to 'UTF-8'
*/
function convToUtf8($str)
{
if(
mb_detect_encoding($str,"UTF-8, ISO-8859-1, GBK")!="UTF-8" )
{

return 
iconv("gbk","utf-8",$str);

}
else
{
return
$str;
}

}
?>
up
1
prgss at bk dot ru
5 years ago
Another light way to detect character encoding:
<?php
function detect_encoding($string) { 
  static
$list = array('utf-8', 'windows-1251');
 
  foreach (
$list as $item) {
   
$sample = iconv($item, $item, $string);
    if (
md5($sample) == md5($string))
      return
$item;
  }
  return
null;
}
?>
up
1
rl at itfigures dot nl
7 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)){
  $str=str_replace("\xE2\x82\xAC","&euro;",$str);
  $str=iconv("UTF-8","ISO-8859-1//TRANSLIT",$str);
  $str=str_replace("&euro;","\x80",$str);
}

If html-output is needed the last line is not necessary (and even unwanted).
up
1
Chrigu
9 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.
up
0
hmdker at gmail dot com
6 years ago
Function to detect UTF-8, when mb_detect_encoding is not available it may be useful.

<?php
function is_utf8($str) {
   
$c=0; $b=0;
   
$bits=0;
   
$len=strlen($str);
    for(
$i=0; $i<$len; $i++){
       
$c=ord($str[$i]);
        if(
$c > 128){
            if((
$c >= 254)) return false;
            elseif(
$c >= 252) $bits=6;
            elseif(
$c >= 248) $bits=5;
            elseif(
$c >= 240) $bits=4;
            elseif(
$c >= 224) $bits=3;
            elseif(
$c >= 192) $bits=2;
            else return
false;
            if((
$i+$bits) > $len) return false;
            while(
$bits > 1){
               
$i++;
               
$b=ord($str[$i]);
                if(
$b < 128 || $b > 191) return false;
               
$bits--;
            }
        }
    }
    return
true;
}
?>
up
0
sunggsun
8 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;
        }
    }
up
0
telemach
9 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('accentue' , '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
up
0
php-note-2005 at ryandesign dot com
9 years ago
Much simpler UTF-8-ness checker using a regular expression created by the W3C:

<?php

// Returns true if $string is valid UTF-8 and false otherwise.
function is_utf8($string) {
   
   
// From http://w3.org/International/questions/qa-forms-utf-8.html
   
return preg_match('%^(?:
          [\x09\x0A\x0D\x20-\x7E]            # ASCII
        | [\xC2-\xDF][\x80-\xBF]             # non-overlong 2-byte
        |  \xE0[\xA0-\xBF][\x80-\xBF]        # excluding overlongs
        | [\xE1-\xEC\xEE\xEF][\x80-\xBF]{2}  # straight 3-byte
        |  \xED[\x80-\x9F][\x80-\xBF]        # excluding surrogates
        |  \xF0[\x90-\xBF][\x80-\xBF]{2}     # planes 1-3
        | [\xF1-\xF3][\x80-\xBF]{3}          # planes 4-15
        |  \xF4[\x80-\x8F][\x80-\xBF]{2}     # plane 16
    )*$%xs'
, $string);
   
}
// function is_utf8

?>
up
0
maarten
9 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:
//    http://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: http://www.xs4all.nl/~mjmeijer/unicode.png and http://www.xs4all.nl/~mjmeijer/unicode2.png
up
-1
matthijs at ischen dot nl
5 years ago
I seriously underestimated the importance of setlocale...
<?php
$strings
= array(
   
"mais coisas a pensar sobre diário ou dois!",
   
"plus de choses à penser à journalier ou à deux !",
   
"¡más cosas a pensar en diario o dos!",
   
"più cose da pensare circa giornaliere o due!",
   
"flere ting å tenke på hver dag eller to!",
   
"Další věcí, přemýšlet o každý den nebo dva!",
   
"mehr über Spaß spät schönen",
   
"më vonë gjatë fun bukur",
   
"több mint szórakozás késő csodálatos kenyér"
);

$convert = array();
setlocale(LC_CTYPE, 'de_DE.UTF-8');
foreach(
$strings as $string )
       
$convert[] = iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $string);
?>

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

<?php
$convert
= array();
setlocale(LC_CTYPE, 'nl_NL.UTF-8');
foreach(
$strings as $string )
       
$convert[] = iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $string);
?>

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.
up
-2
eyecatchup at gmail dot com
1 year ago
Just a note: Instead of using the often recommended (rather complex) regular expression by W3C (http://www.w3.org/International/questions/qa-forms-utf-8.en.php), you can simply use the 'u' modifier to test a string for UTF-8 validity:

<?php
 
if (preg_match("//u", $string)) {
     
// $string is valid UTF-8
 
}
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