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mb_detect_encoding

(PHP 4 >= 4.0.6, PHP 5)

mb_detect_encoding — 检测字符的编码

说明

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

检测字符串 str 的编码。

参数

str

待检查的字符串。

encoding_list

encoding_list 是一个字符编码列表。编码顺序可以由数组或者逗号分隔的列表字符串指定。

如果省略了 encoding_list 将会使用 detect_order。

strict

strict 指定了是否严格地检测编码。默认是 FALSE 。

返回值

检测到的字符编码，或者无法检测指定字符串的编码时返回 FALSE 。

范例

Example #1 mb_detect_encoding() 例子

  <?php
 
 echo  mb_detect_encoding ( $str );

 
 echo  mb_detect_encoding ( $str ,  "auto" );

 
 echo  mb_detect_encoding ( $str ,  "JIS, eucjp-win, sjis-win" );

 
 $ary [] =  "ASCII" ;
 $ary [] =  "JIS" ;
 $ary [] =  "EUC-JP" ;
echo  mb_detect_encoding ( $str ,  $ary );
 ?>

参见

mb_detect_order() - 设置/获取字符编码的检测顺序

用户评论:

[#1] thinkxf at gmail dot com [2014-10-08 05:32:15]

if you want to use this function ,you must loadmodule php_mbstring in the php.ini.

[#2] emoebel at web dot de [2013-12-25 09:29:57]

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);

[#3] Anonymous [2013-10-08 21:17:06]

// -----------------------------------------------------------

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;
}

}

// -----------------------------------------------------------

[#4] eyecatchup at gmail dot com [2013-06-11 10:41:41]

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
  }

[#5] bmrkbyet at web dot de [2013-03-24 14:04:36]

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

[#6] Gerg Tisza [2011-02-18 03:43:45]

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 $str = '????????'; // ISO-8859-1 mb_detect_encoding($str, 'UTF-8'); // 'UTF-8' mb_detect_encoding($str, 'UTF-8', true); // false ?>

[#7] nat3738 at gmail dot com [2009-05-22 03:58:04]

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'; } ?>

[#8] prgss at bk dot ru [2009-03-30 02:16:22]

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; } ?>

[#9] matthijs at ischen dot nl [2009-03-28 10:33:20]

I seriously underestimated the importance of setlocale...
<?php $strings = array(     "mais coisas a pensar sobre di??rio ou dois!",     "plus de choses ?? penser ?? journalier ou ?? deux !",     "?m??s cosas a pensar en diario o dos!",     "pi?? cose da pensare circa giornaliere o due!",     "flere ting ? tenke p? hver dag eller to!",     "Dal??? v??c??, p?em??let o ka?d? den nebo dva!",     "mehr ??ber Spa? sp?t sch?nen",     "m? von? gjat? fun bukur",     "t?bb mint sz??rakoz??s k??s? csod??latos keny??r" ); $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.

[#10] dennis at nikolaenko dot ru [2008-10-06 09:18:05]

Beware of bug to detect Russian encodings
http://bugs.php.net/bug.php?id=38138

[#11] hmdker at gmail dot com [2008-08-23 21:58:28]

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; } ?>

[#12] yaqy at qq dot com [2008-07-20 22:14:56]

<?php 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; } } ?>

[#13] rl at itfigures dot nl [2007-09-04 14:00:15]

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).

[#14] sunggsun [2006-08-15 00:26:19]

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;
        }
    }

[#15] chris AT w3style.co DOT uk [2006-08-03 02:22:16]

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); } ?>

[#16] telemach [2005-07-27 18:48:52]

[#17] Chrigu [2005-03-29 07:32:23]

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.

[#18] php-note-2005 at ryandesign dot com [2005-02-17 07:57:14]

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 ?>

[#19] jaaks at playtech dot com [2005-01-14 00:27:05]

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

[#20] maarten [2005-01-12 15:55:40]

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