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

Коментарии

Автор:
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
2005-01-12 17:55:40
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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

?>
2005-02-17 09:57:14
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
Автор:
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.
2005-03-29 10:32:23
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
Автор:
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
2005-07-27 21:48:52
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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);
}

?>
2006-08-03 05:22:16
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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).
2007-09-04 17:00:15
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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;
}
?>
2008-08-24 00:58:28
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
Beware of bug to detect Russian encodings
http://bugs.php.net/bug.php?id=38138
2008-10-06 12:18:05
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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);
   
$first2 substr($text02);
   
$first3 substr($text03);
   
$first4 substr($text03);
   
    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';
}
?>
2009-05-22 06:58:04
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
Автор:
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
?>
2011-02-18 05:43:45
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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
}
}

// -------------------------------------------
?>
2013-03-24 16:04:36
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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
 
}
2013-06-11 13:41:41
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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);
2013-12-25 11:29:57
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
<?php
$file 
file_get_contents("somefile.txt");
$encodings implode(','mb_list_encodings());
echo 
mb_detect_encoding($file$encodingstrue);
?>
seems to work
2016-11-06 14:54:22
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
For detect UTF-8, you can use:

if (preg_match('!!u', $str)) { echo 'utf-8'; }

- Norihiori
2017-03-30 16:11:28
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
About function mb_detect_encoding, the link http://php.net/manual/zh/function.mb-detect-encoding.php , like this:
mb_detect_encoding('áéóú', 'UTF-8', true); // false
but now the result is not false, can you give me reason, thanks!
2018-01-04 14:18:56
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
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.
2018-03-28 10:17:39
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
Автор:
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);
2022-04-04 16:48:37
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
The documentation is no longer correct for php8.1 and mb_detect_encoding no longer supports order of encodings. The example outputs given in the documentation are also no longer correct for php8.1. This is somewhat explained here https://github.com/php/php-src/issues/8279

I understand the previous ambiguity in these functions, but in my option 8.1 should have deprecated mb_detect_encoding and mb_detect_order and came up with different functions. It now tries to find the encoding that will use the least amount of space regardless of the order, and I am not sure who needs that.

Below is an example function that will do what mb_detect_encoding was doing prior to the 8.1 change.

<?php

function mb_detect_enconding_in_order(string $string, array $encodings): string|false
{
    foreach(
$encodings as $enc) {
        if (
mb_check_encoding($string$enc)) {
            return 
$enc;
        }
    }
    return 
false;
}

?>
2022-09-19 10:47:12
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html
Major undocumented breaking change since 8.1.7
https://3v4l.org/BLjZ3

Make sure to replace mb_detect_encoding with a loop of calls to mb_check_encoding
2022-11-09 00:35:17
http://php5.kiev.ua/manual/ru/function.mb-detect-encoding.html

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