mb_convert_encoding()

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

转换字符的编码

说明

mb_convert_encoding(string $str,string $to_encoding[,mixed $from_encoding= mb_internal_encoding()]): string

将string类型$str的字符编码从可选的$from_encoding转换到$to_encoding。

参数

$str

要编码的string。

$to_encoding

$str要转换成的编码类型。

$from_encoding

在转换前通过字符代码名称来指定。它可以是一个array也可以是逗号分隔的枚举列表。如果没有提供$from_encoding，则会使用内部（internal）编码。

参见支持的编码。

返回值

编码后的string。

范例

mb_convert_encoding()例子

<?php
/* 转换内部编码为 SJIS */
$str = mb_convert_encoding($str, "SJIS");
/* 将 EUC-JP 转换成 UTF-7 */
$str = mb_convert_encoding($str, "UTF-7", "EUC-JP");
/* 从 JIS, eucjp-win, sjis-win 中自动检测编码，并转换 str 到 UCS-2LE */
$str = mb_convert_encoding($str, "UCS-2LE", "JIS, eucjp-win, sjis-win");
/* "auto" 扩展成 "ASCII,JIS,UTF-8,EUC-JP,SJIS" */
$str = mb_convert_encoding($str, "EUC-JP", "auto");
?>

参见

• mb_detect_order()设置/获取字符编码的检测顺序

For my last project I needed to convert several CSV files from Windows-1250 to UTF-8, and after several days of searching around I found a function that is partially solved my problem, but it still has not transformed all the characters. So I made ​​this:
function w1250_to_utf8($text) {
  // map based on:
  // http://konfiguracja.c0.pl/iso02vscp1250en.html
  // http://konfiguracja.c0.pl/webpl/index_en.html#examp
  // http://www.htmlentities.com/html/entities/
  $map = array(
    chr(0x8A) => chr(0xA9),
    chr(0x8C) => chr(0xA6),
    chr(0x8D) => chr(0xAB),
    chr(0x8E) => chr(0xAE),
    chr(0x8F) => chr(0xAC),
    chr(0x9C) => chr(0xB6),
    chr(0x9D) => chr(0xBB),
    chr(0xA1) => chr(0xB7),
    chr(0xA5) => chr(0xA1),
    chr(0xBC) => chr(0xA5),
    chr(0x9F) => chr(0xBC),
    chr(0xB9) => chr(0xB1),
    chr(0x9A) => chr(0xB9),
    chr(0xBE) => chr(0xB5),
    chr(0x9E) => chr(0xBE),
    chr(0x80) => '€',
    chr(0x82) => '‚',
    chr(0x84) => '„',
    chr(0x85) => '…',
    chr(0x86) => '†',
    chr(0x87) => '‡',
    chr(0x89) => '‰',
    chr(0x8B) => '‹',
    chr(0x91) => '‘',
    chr(0x92) => '’',
    chr(0x93) => '“',
    chr(0x94) => '”',
    chr(0x95) => '•',
    chr(0x96) => '–',
    chr(0x97) => '—',
    chr(0x99) => '™',
    chr(0x9B) => '’',
    chr(0xA6) => '¦',
    chr(0xA9) => '©',
    chr(0xAB) => '«',
    chr(0xAE) => '®',
    chr(0xB1) => '±',
    chr(0xB5) => 'µ',
    chr(0xB6) => '¶',
    chr(0xB7) => '·',
    chr(0xBB) => '»',
  );
  return html_entity_decode(mb_convert_encoding(strtr($text, $map), 'UTF-8', 'ISO-8859-2'), ENT_QUOTES, 'UTF-8');
}

I've been trying to find the charset of a norwegian (with a lot of ø, æ, å) txt file written on a Mac, i've found it in this way:
<?php
$text = "A strange string to pass, maybe with some ø, æ, å characters.";
foreach(mb_list_encodings() as $chr){
    echo mb_convert_encoding($text, 'UTF-8', $chr)." : ".$chr."<br>";  
 } 
?>
The line that looks good, gives you the encoding it was written in.
Hope can help someone

aaron, to discard unsupported characters instead of printing a ?, you might as well simply set the configuration directive:
mbstring.substitute_character = "none"
in your php.ini. Be sure to include the quotes around none. Or at run-time with
<?php
ini_set('mbstring.substitute_character', "none");
?>

Hey guys. For everybody who's looking for a function that is converting an iso-string to utf8 or an utf8-string to iso, here's your solution:
public function encodeToUtf8($string) {
   return mb_convert_encoding($string, "UTF-8", mb_detect_encoding($string, "UTF-8, ISO-8859-1, ISO-8859-15", true));
}
public function encodeToIso($string) {
   return mb_convert_encoding($string, "ISO-8859-1", mb_detect_encoding($string, "UTF-8, ISO-8859-1, ISO-8859-15", true));
}
For me these functions are working fine. Give it a try

many people below talk about using 
<?php
  mb_convert_encode($s,'HTML-ENTITIES','UTF-8');
?>
to convert non-ascii code into html-readable stuff. Due to my webserver being out of my control, I was unable to set the database character set, and whenever PHP made a copy of my $s variable that it had pulled out of the database, it would convert it to nasty latin1 automatically and not leave it in it's beautiful UTF-8 glory.
So [insert korean characters here] turned into ?????.
I found myself needing to pass by reference (which of course is deprecated/nonexistent in recent versions of PHP)
so instead of
<?php
  mb_convert_encode(&$s,'HTML-ENTITIES','UTF-8');
?>
which worked perfectly until I upgraded, so I had to use
<?php
  call_user_func_array('mb_convert_encoding', array(&$s,'HTML-ENTITIES','UTF-8'));
?>
Hope it helps someone else out

My solution below was slightly incorrect, so here is the correct version (I posted at the end of a long day, never a good idea!)
Again, this is a quick and dirty solution to stop mb_convert_encoding from filling your string with question marks whenever it encounters an illegal character for the target encoding. 
<?php
function convert_to ( $source, $target_encoding )
  {
  // detect the character encoding of the incoming file
  $encoding = mb_detect_encoding( $source, "auto" );
    
  // escape all of the question marks so we can remove artifacts from
  // the unicode conversion process
  $target = str_replace( "?", "[question_mark]", $source );
    
  // convert the string to the target encoding
  $target = mb_convert_encoding( $target, $target_encoding, $encoding);
    
  // remove any question marks that have been introduced because of illegal characters
  $target = str_replace( "?", "", $target );
    
  // replace the token string "[question_mark]" with the symbol "?"
  $target = str_replace( "[question_mark]", "?", $target );
  
  return $target;
  }
?>
Hope this helps someone! (Admins should feel free to delete my previous, incorrect, post for clarity)
-A

To add to the Flash conversion comment below, here's how I convert back from what I've stored in a database after converting from Flash HTML text field output, in order to load it back into a Flash HTML text field:
function htmltoflash($htmlstr)
{
 return str_replace("<br />","\n",
  str_replace("<","&lt;",
   str_replace(">","&gt;",
    mb_convert_encoding(html_entity_decode($htmlstr),
    "UTF-8","ISO-8859-1"))));
}

Why did you use the php html encode functions? mbstring has it's own Encoding which is (as far as I tested it) much more usefull:
HTML-ENTITIES
Example:
$text = mb_convert_encoding($text, 'HTML-ENTITIES', "UTF-8");

instead of ini_set(), you can try this
mb_substitute_character("none");

It appears that when dealing with an unknown "from encoding" the function will both throw an E_WARNING and proceed to convert the string from ISO-8859-1 to the "to encoding".

For those wanting to convert from $set to MacRoman, use iconv():
<?php
$string = iconv('UTF-8', 'macintosh', $string);
?>
('macintosh' is the IANA name for the MacRoman character set.)

If you are trying to generate a CSV (with extended chars) to be opened at Exel for Mac, the only that worked for me was:
<?php mb_convert_encoding( $CSV, 'Windows-1252', 'UTF-8'); ?>
I also tried this:
<?php
//Separado OK, chars MAL
iconv('MACINTOSH', 'UTF8', $CSV);
//Separado MAL, chars OK
chr(255).chr(254).mb_convert_encoding( $CSV, 'UCS-2LE', 'UTF-8');
?>
But the first one didn't show extended chars correctly, and the second one, did't separe fields correctly

Clean a string for use as filename by simply replacing all unwanted characters with underscore (ASCII converts to 7bit). It removes slightly more chars than necessary. Hope its useful. 
$fileName = 'Test:!"$%&/()=ÖÄÜöäü<<';
echo strtr(mb_convert_encoding($fileName,'ASCII'), 
  ' ,;:?*#!§$%&/(){}<>=`´|\\\'"', 
  '____________________________');

Note that `mb_convert_encoding($val, 'HTML-ENTITIES')` does not escape '\'', '"', '<', '>', or '&'.

When you need to convert from HTML-ENTITIES, but your UTF-8 string is partially broken (not all chars in UTF-8) - in this case passing string to mb_convert_encoding($string, 'UTF-8', 'HTML-ENTITIES'); - corrupts chars in string even more. In this case you need to replace html entities gradually to preserve character good encoding. I wrote such closure for this job :
<?php
$decode_entities = function($string) {
    preg_match_all("/&#?\w+;/", $string, $entities, PREG_SET_ORDER);
    $entities = array_unique(array_column($entities, 0));
    foreach ($entities as $entity) {
      $decoded = mb_convert_encoding($entity, 'UTF-8', 'HTML-ENTITIES');
      $string = str_replace($entity, $decoded, $string);
    }
    return $string;
  };
?>

// convert UTF8 to DOS = CP850 
//
// $utf8_text=UTF8-Formatted text;
// $dos=CP850-Formatted text;
// have fun
$dos = mb_convert_encoding($utf8_text, "CP850", mb_detect_encoding($utf8_text, "UTF-8, CP850, ISO-8859-15", true));

rodrigo at bb2 dot co dot jp wrote that inconv works better than mb_convert_encoding, I find that when converting from uft8 to shift_jis 
$conv_str = mb_convert_encoding($str,$toCS,$fromCS); 
works while
$conv_str = iconv($fromCS,$toCS.'//IGNORE',$str); 
removes tildes from $str.

When converting Japanese strings to ISO-2022-JP or JIS on PHP >= 5.2.1, you can use "ISO-2022-JP-MS" instead of them.
Kishu-Izon (platform dependent) characters are converted correctly with the encoding, as same as with eucJP-win or with SJIS-win.

Another sample of recoding without MultiByte enabling.
(Russian koi->win, if input in win-encoding already, function recode() returns unchanged string)
<?php
 // 0 - win
 // 1 - koi
 function detect_encoding($str) {
  $win = 0;
  $koi = 0;
  for($i=0; $i<strlen($str); $i++) {
   if( ord($str[$i]) >224 && ord($str[$i]) < 255) $win++;
   if( ord($str[$i]) >192 && ord($str[$i]) < 223) $koi++;
  }
  if( $win < $koi ) {
   return 1;
  } else return 0;
 }
 // recodes koi to win
 function koi_to_win($string) {
  $kw = array(128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 254, 224, 225, 246, 228, 229, 244, 227, 245, 232, 233, 234, 235, 236, 237, 238, 239, 255, 240, 241, 242, 243, 230, 226, 252, 251, 231, 248, 253, 249, 247, 250, 222, 192, 193, 214, 196, 197, 212, 195, 213, 200, 201, 202, 203, 204, 205, 206, 207, 223, 208, 209, 210, 211, 198, 194, 220, 219, 199, 216, 221, 217, 215, 218);
  $wk = array(128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 225, 226, 247, 231, 228, 229, 246, 250, 233, 234, 235, 236, 237, 238, 239, 240, 242, 243, 244, 245, 230, 232, 227, 254, 251, 253, 255, 249, 248, 252, 224, 241, 193, 194, 215, 199, 196, 197, 214, 218, 201, 202, 203, 204, 205, 206, 207, 208, 210, 211, 212, 213, 198, 200, 195, 222, 219, 221, 223, 217, 216, 220, 192, 209);
  $end = strlen($string);
  $pos = 0;
  do {
   $c = ord($string[$pos]);
   if ($c>128) {
    $string[$pos] = chr($kw[$c-128]);
   }
  } while (++$pos < $end);
  return $string;
 }
 function recode($str) {
  $enc = detect_encoding($str);
  if ($enc==1) {
   $str = koi_to_win($str);
  }
  return $str;
 }
?>

As an alternative to Johannes's suggestion for converting strings from other character sets to a 7bit representation while not just deleting latin diacritics, you might try this:
<?php
$text = iconv($from_enc, 'US-ASCII//TRANSLIT', $text);
?>
The only disadvantage is that it does not convert "ä" to "ae", but it handles punctuation and other special characters better.
-- 
David

Here's a tip for anyone using Flash and PHP for storing HTML output submitted from a Flash text field in a database or whatever.
Flash submits its HTML special characters in UTF-8, so you can use the following function to convert those into HTML entity characters:
function utf8html($utf8str)
{
 return htmlentities(mb_convert_encoding($utf8str,"ISO-8859-1","UTF-8"));
}

When using the Windows Notepad text editor, it is important to note that when you select 'Save As' there is an Encoding selection dropdown. The default encoding is set to ANSI, with the other two options being Unicode and UTF-8. Since most text on the web is in UTF-8 format it could prove vital to save the .txt file with this encoding, since this function does not work on ANSI-encoded text.

mb_substr and probably several other functions works faster in ucs-2 than in utf-8. and utf-16 works slower than utf-8. here is test, ucs-2 is near 50 times faster than utf-8, and utf-16 is near 6 times slower than utf-8 here:
<?php
header('Content-Type: text/html; charset=utf-8');
mb_internal_encoding('utf-8');
$s='укгезәөшөхзәхөшк2049һһлдябчсячмииюсит.июбҗрарэ'
.'лдэфвәәуүйәуйүәу034928348539857әшаыдларорашһһрлоавы';
$s.=$s;
$s.=$s;
$s.=$s;
$s.=$s;
$s.=$s;
$s.=$s;
$s.=$s;
$t1=microtime(true);
$i=0;
while($i<mb_strlen($s)){
  $a=mb_substr($s,$i,2);
  $i+=2;
  if($i==10)echo$a.'. ';
  //echo$a.'. ';
}
echo$i.'. ';
echo(microtime(true)-$t1);
echo'<br>';
$s=mb_convert_encoding($s,'UCS-2','utf8');
mb_internal_encoding('UCS-2');
$t1=microtime(true);
$i=0;
while($i<mb_strlen($s)){
  $a=mb_substr($s,$i,2);
  $i+=2;
  if($i==10)echo mb_convert_encoding($a,'utf8','ucs2').'. ';
  //echo$a.'. ';
}
echo$i.'. ';
echo(microtime(true)-$t1);
echo'<br>';
$s=mb_convert_encoding($s,'utf-16','ucs-2');
mb_internal_encoding('utf-16');
$t1=microtime(true);
$i=0;
while($i<mb_strlen($s)){
  $a=mb_substr($s,$i,2);
  $i+=2;
  if($i==10)echo mb_convert_encoding($a,'utf8','utf-16').'. ';
  //echo$a.'. ';
}
echo$i.'. ';
echo(microtime(true)-$t1);
?>
output:
өх. 12416. 1.71738100052
өх. 12416. 0.0211279392242
өх. 12416. 11.2330229282

If you are attempting to convert "UTF-8" text to "ISO-8859-1" and the result is always returning in "ASCII", place the following line of code before the mb_convert_encoding:
mb_detect_order(array('UTF-8', 'ISO-8859-1'));
It is necessary to force a specific search order for the conversion to work

For the php-noobs (like me) - working with flash and php.
Here's a simple snippet of code that worked great for me, getting php to show special Danish characters, from a Flash email form:
<?php
// Name Escape
$escName = mb_convert_encoding($_POST["Name"], "ISO-8859-1", "UTF-8");
// message escape
$escMessage = mb_convert_encoding($_POST["Message"], "ISO-8859-1", "UTF-8");
// Headers.. and so on...
?>

For those who can´t use mb_convert_encoding() to convert from one charset to another as a metter of lower version of php, try iconv().
I had this problem converting to japanese charset:
$txt=mb_convert_encoding($txt,'SJIS',$this->encode);
And I could fix it by using this:
$txt = iconv('UTF-8', 'SJIS', $txt);
Maybe it´s helpfull for someone else! ;)

To petruzanauticoyahoo?com!ar
If you don't specify a source encoding, then it assumes the internal (default) encoding. ñ is a multi-byte character whose bytes in your configuration default (often iso-8859-1) would actually mean ñ. mb_convert_encoding() is upgrading those characters to their multi-byte equivalents within UTF-8.
Try this instead:
<?php
print mb_convert_encoding( "ñ", "UTF-8", "UTF-8" );
?>
Of course this function does no work (for the most part - it can actually be used to strip characters which are not valid for UTF-8).

I\'d like to share some code to convert latin diacritics to their
traditional 7bit representation, like, for example,
- à,ç,é,î,... to a,c,e,i,...
- ß to ss
- ä,Ä,... to ae,Ae,...
- ë,... to e,...
(mb_convert \"7bit\" would simply delete any offending characters). 
I might have missed on your country\'s typographic 
conventions--correct me then. 
<?php
/**
 * @args string $text line of encoded text
 *    string $from_enc (encoding type of $text, e.g. UTF-8, ISO-8859-1)
 *
 * @returns 7bit representation
 */
function to7bit($text,$from_enc) {
  $text = mb_convert_encoding($text,\'HTML-ENTITIES\',$from_enc);
  $text = preg_replace(
    array(\'/ß/\',\'/&(..)lig;/\',
       \'/&([aouAOU])uml;/\',\'/&(.)[^;]*;/\'),
    array(\'ss\',\"$1\",\"$1\".\'e\',\"$1\"),
    $text);
  return $text;
}  
?>
Enjoy :-)
Johannes
==
[EDIT BY danbrown AT php DOT net: Author provided the following update on 27-FEB-2012.]
==
An addendum to my "to7bit" function referenced below in the notes. 
The function is supposed to solve the problem that some languages require a different 7bit rendering of special (umlauted) characters for sorting or other applications. For example, the German ß ligature is usually written "ss" in 7bit context. Dutch ÿ is typically rendered "ij" (not "y"). 
The original function works well with word (alphabet) character entities and I've seen it used in many places. But non-word entities cause funny results:
E.g., "©" is rendered as "c", "­" as "s" and "&rquo;" as "r". 
The following version fixes this by converting non-alphanumeric characters (also chains thereof) to '_'.
<?php
/**
 * @args string $text line of encoded text
 *    string $from_enc (encoding type of $text, e.g. UTF-8, ISO-8859-1)
 *
 * @returns 7bit representation
 */
function to7bit($text,$from_enc) {
  $text = preg_replace(/W+/,'_',$text);
  $text = mb_convert_encoding($text,'HTML-ENTITIES',$from_enc);
  $text = preg_replace(
    array('/ß/','/&(..)lig;/',
       '/&([aouAOU])uml;/','/ÿ/','/&(.)[^;]*;/'),
    array('ss',"$1","$1".'e','ij',"$1"),
    $text);
  return $text;
} 
?>
Enjoy again,
Johannes

// mb_convert_encoding($input,'UTF-8','windows-874'); error : Illegal character encoding specified
// so convert Thai to UTF-8 is better use iconv instead
<?php
iconv("windows-874","UTF-8",$input);
?>

If mb_convert_encoding doesn't work for you, and iconv gives you a headache, you might be interested in this free class I found. It can convert almost any charset to almost any other charset. I think it's wonderful and I wish I had found it earlier. It would have saved me tons of headache.
I use it as a fail-safe, in case mb_convert_encoding is not installed. Download it from http://mikolajj.republika.pl/
This is not my own library, so technically it's not spamming, right? ;)
Hope this helps.

If you want to convert japanese to ISO-2022-JP it is highly recommended to use ISO-2022-JP-MS as the target encoding instead. This includes the extended character set and avoids ? in the text. For example the often used "1 in a circle" ① will be correctly converted then.

be careful when converting from iso-8859-1 to utf-8.
even if you explicitly specify the character encoding of a page as iso-8859-1(via headers and strict xml defs), windows 2000 will ignore that and interpret it as whatever character set it has natively installed. 
for example, i wrote char #128 into a page, with char encoding iso-8859-1, and it displayed in internet explorer (& mozilla) as a euro symbol.
it should have displayed a box, denoting that char #128 is undefined in iso-8859-1. The problem was it was displaying in "Windows: western europe" (my native character set).
this led to confusion when i tried to convert this euro to UTF-8 via mb_convert_encoding() 
IE displays UTF-8 correctly- and because PHP correctly converted #128 into a box in UTF-8, IE would show a box.
so all i saw was mb_convert_encoding() converting a euro symbol into a box. It took me a long time to figure out what was going on.