PHP: Convert unicode codepoint to UTF-8

function utf8($num)
{
    if($num<=0x7F)       return chr($num);
    if($num<=0x7FF)      return chr(($num>>6)+192).chr(($num&63)+128);
    if($num<=0xFFFF)     return chr(($num>>12)+224).chr((($num>>6)&63)+128).chr(($num&63)+128);
    if($num<=0x1FFFFF)   return chr(($num>>18)+240).chr((($num>>12)&63)+128).chr((($num>>6)&63)+128).chr(($num&63)+128);
    return '';
}

function uniord($c)
{
    $ord0 = ord($c{0}); if ($ord0>=0   && $ord0<=127) return $ord0;
    $ord1 = ord($c{1}); if ($ord0>=192 && $ord0<=223) return ($ord0-192)*64 + ($ord1-128);
    $ord2 = ord($c{2}); if ($ord0>=224 && $ord0<=239) return ($ord0-224)*4096 + ($ord1-128)*64 + ($ord2-128);
    $ord3 = ord($c{3}); if ($ord0>=240 && $ord0<=247) return ($ord0-240)*262144 + ($ord1-128)*4096 + ($ord2-128)*64 + ($ord3-128);
    return false;
}

utf8() and uniord() try to mirror the chr() and ord() functions on php:

echo utf8(0x6211)."\n";
echo uniord(utf8(0x6211))."\n";
echo "U+".dechex(uniord(utf8(0x6211)))."\n";

//In your case:
$wo='U+6211';
$hao='U+597D';
echo utf8(hexdec(str_replace("U+","", $wo)))."\n";
echo utf8(hexdec(str_replace("U+","", $hao)))."\n";

output:

我
25105
U+6211
我
好

PHP 7+

As of PHP 7, you can use the Unicode codepoint escape syntax to do this.

echo "\u{597D}"; outputs 好.

I just wrote a polyfill for missing multibyte versions of ord and chr with the following in mind:

• It defines functions mb_ord and mb_chr only if they don't already exist. If they do exist in your framework or some future version of PHP, the polyfill will be ignored.

• It uses the widely used mbstring extension to do the conversion. If the mbstring extension is not loaded, it will use the iconv extension instead.

I also added functions for HTMLentities encoding / decoding and encoding / decoding to JSON format as well as some demo code for how to use these functions

Code

if (!function_exists('codepoint_encode')) {
    function codepoint_encode($str) {
        return substr(json_encode($str), 1, -1);
    }
}

if (!function_exists('codepoint_decode')) {
    function codepoint_decode($str) {
        return json_decode(sprintf('"%s"', $str));
    }
}

if (!function_exists('mb_internal_encoding')) {
    function mb_internal_encoding($encoding = NULL) {
        return ($from_encoding === NULL) ? iconv_get_encoding() : iconv_set_encoding($encoding);
    }
}

if (!function_exists('mb_convert_encoding')) {
    function mb_convert_encoding($str, $to_encoding, $from_encoding = NULL) {
        return iconv(($from_encoding === NULL) ? mb_internal_encoding() : $from_encoding, $to_encoding, $str);
    }
}

if (!function_exists('mb_chr')) {
    function mb_chr($ord, $encoding = 'UTF-8') {
        if ($encoding === 'UCS-4BE') {
            return pack("N", $ord);
        } else {
            return mb_convert_encoding(mb_chr($ord, 'UCS-4BE'), $encoding, 'UCS-4BE');
        }
    }
}

if (!function_exists('mb_ord')) {
    function mb_ord($char, $encoding = 'UTF-8') {
        if ($encoding === 'UCS-4BE') {
            list(, $ord) = (strlen($char) === 4) ? @unpack('N', $char) : @unpack('n', $char);
            return $ord;
        } else {
            return mb_ord(mb_convert_encoding($char, 'UCS-4BE', $encoding), 'UCS-4BE');
        }
    }
}

if (!function_exists('mb_htmlentities')) {
    function mb_htmlentities($string, $hex = true, $encoding = 'UTF-8') {
        return preg_replace_callback('/[\x{80}-\x{10FFFF}]/u', function ($match) use ($hex) {
            return sprintf($hex ? '&#x%X;' : '&#%d;', mb_ord($match[0]));
        }, $string);
    }
}

if (!function_exists('mb_html_entity_decode')) {
    function mb_html_entity_decode($string, $flags = null, $encoding = 'UTF-8') {
        return html_entity_decode($string, ($flags === NULL) ? ENT_COMPAT | ENT_HTML401 : $flags, $encoding);
    }
}

How to use

echo "\nGet string from numeric DEC value\n";
var_dump(mb_chr(25105));
var_dump(mb_chr(22909));

echo "\nGet string from numeric HEX value\n";
var_dump(mb_chr(0x6211));
var_dump(mb_chr(0x597D));

echo "\nGet numeric value of character as DEC int\n";
var_dump(mb_ord('我'));
var_dump(mb_ord('好'));

echo "\nGet numeric value of character as HEX string\n";
var_dump(dechex(mb_ord('我')));
var_dump(dechex(mb_ord('好')));

echo "\nEncode / decode to DEC based HTML entities\n";
var_dump(mb_htmlentities('我好', false));
var_dump(mb_html_entity_decode('我好'));

echo "\nEncode / decode to HEX based HTML entities\n";
var_dump(mb_htmlentities('我好'));
var_dump(mb_html_entity_decode('我好'));

echo "\nUse JSON encoding / decoding\n";
var_dump(codepoint_encode("我好"));
var_dump(codepoint_decode('\u6211\u597d'));

Output

Get string from numeric DEC value
string(3) "我"
string(3) "好"

Get string from numeric HEX value
string(3) "我"
string(3) "好"

Get numeric value of character as DEC string
int(25105)
int(22909)

Get numeric value of character as HEX string
string(4) "6211"
string(4) "597d"

Encode / decode to DEC based HTML entities
string(16) "我好"
string(6) "我好"

Encode / decode to HEX based HTML entities
string(16) "我好"
string(6) "我好"

Use JSON encoding / decoding
string(12) "\u6211\u597d"
string(6) "我好"

mb_convert_encoding(
    preg_replace("/U\+([0-9A-F]*)/"
        ,"&#x\\1;"
        ,'U+597DU+6211'
    )
    ,"UTF-8"
    ,"HTML-ENTITIES"
);

works fine, too.

<?php

function chr_utf8($n,$f='C*'){
return $n<(1<<7)?chr($n):($n<1<<11?pack($f,192|$n>>6,1<<7|191&$n):
($n<(1<<16)?pack($f,224|$n>>12,1<<7|63&$n>>6,1<<7|63&$n):
($n<(1<<20|1<<16)?pack($f,240|$n>>18,1<<7|63&$n>>12,1<<7|63&$n>>6,1<<7|63&$n):'')));
}

$your_input='U+597D';

echo (chr_utf8(hexdec(ltrim($your_input,'U+'))));

// Output 好

If you want to use a callback function you can try it :

<?php

// Note: function chr_utf8 shown above is required

$your_input='U+597DU+6211';

$result=preg_replace_callback('#U\+([a-f0-9]+)#i',function($a){return chr_utf8(hexdec($a[1]));},$your_input);

echo $result;

// Output 好我

Check it in https://eval.in/748187

I was in the position I needed to filter specific characters without affecting the html because I was using a wysiwig editor, but people copy pasting from word would add some nice unrenderable characters to the content.

My solution boils down to simple replacement lists.

class ReplaceIllegal {
    public static $find = array ( 0 => '\x0', 1 => '\x1', 2 => '\x2', 3 => '\x3', 4 => '\x4', 5 => '\x5', 6 => '\x6', 7 => '\x7', 8 => '\x8', 9 => '\x9', 10 => '\xA', 11 => '\xB', 12 => '\xC', 13 => '\xD', 14 => '\xE', 15 => '\xF', 16 => '\x10', 17 => '\x11', 18 => '\x12', 19 => '\x13', 20 => '\x14', 21 => '\x15', 22 => '\x16', 23 => '\x17', 24 => '\x18', 25 => '\x19', 26 => '\x1A', 27 => '\x1B', 28 => '\x1C', 29 => '\x1D', 30 => '\x1E', 31 => '\x80', 32 => '\x81', 33 => '\x82', 34 => '\x83', 35 => '\x84', 36 => '\x85', 37 => '\x86', 38 => '\x87', 39 => '\x88', 40 => '\x89', 41 => '\x8A', 42 => '\x8B', 43 => '\x8C', 44 => '\x8D', 45 => '\x8E', 46 => '\x8F', 47 => '\x90', 48 => '\x91', 49 => '\x92', 50 => '\x93', 51 => '\x94', 52 => '\x95', 53 => '\x96', 54 => '\x97', 55 => '\x98', 56 => '\x99', 57 => '\x9A', 58 => '\x9B', 59 => '\x9C', 60 => '\x9D', 61 => '\x9E', 62 => '\x9F', 63 => '\xA0', 64 => '\xA1', 65 => '\xA2', 66 => '\xA3', 67 => '\xA4', 68 => '\xA5', 69 => '\xA6', 70 => '\xA7', 71 => '\xA8', 72 => '\xA9', 73 => '\xAA', 74 => '\xAB', 75 => '\xAC', 76 => '\xAD', 77 => '\xAE', 78 => '\xAF', 79 => '\xB0', 80 => '\xB1', 81 => '\xB2', 82 => '\xB3', 83 => '\xB4', 84 => '\xB5', 85 => '\xB6', 86 => '\xB7', 87 => '\xB8', 88 => '\xB9', 89 => '\xBA', 90 => '\xBB', 91 => '\xBC', 92 => '\xBD', 93 => '\xBE', 94 => '\xBF', 95 => '\xC0', 96 => '\xC1', 97 => '\xC2', 98 => '\xC3', 99 => '\xC4', 100 => '\xC5', 101 => '\xC6', 102 => '\xC7', 103 => '\xC8', 104 => '\xC9', 105 => '\xCA', 106 => '\xCB', 107 => '\xCC', 108 => '\xCD', 109 => '\xCE', 110 => '\xCF', 111 => '\xD0', 112 => '\xD1', 113 => '\xD2', 114 => '\xD3', 115 => '\xD4', 116 => '\xD5', 117 => '\xD6', 118 => '\xD7', 119 => '\xD8', 120 => '\xD9', 121 => '\xDA', 122 => '\xDB', 123 => '\xDC', 124 => '\xDD', 125 => '\xDE', 126 => '\xDF', 127 => '\xE0', 128 => '\xE1', 129 => '\xE2', 130 => '\xE3', 131 => '\xE4', 132 => '\xE5', 133 => '\xE6', 134 => '\xE7', 135 => '\xE8', 136 => '\xE9', 137 => '\xEA', 138 => '\xEB', 139 => '\xEC', 140 => '\xED', 141 => '\xEE', 142 => '\xEF', 143 => '\xF0', 144 => '\xF1', 145 => '\xF2', 146 => '\xF3', 147 => '\xF4', 148 => '\xF5', 149 => '\xF6', 150 => '\xF7', 151 => '\xF8', 152 => '\xF9', 153 => '\xFA', 154 => '\xFB', 155 => '\xFC', 156 => '\xFD', 157 => '\xFE', );
    private static $replace = array ( 0 => '�', 1 => '', 2 => '', 3 => '', 4 => '', 5 => '', 6 => '', 7 => '', 8 => '', 9 => '	', 10 => '
', 11 => '', 12 => '', 13 => '
', 14 => '', 15 => '', 16 => '', 17 => '', 18 => '', 19 => '', 20 => '', 21 => '', 22 => '', 23 => '', 24 => '', 25 => '', 26 => '', 27 => '', 28 => '', 29 => '', 30 => '', 31 => '€', 32 => '', 33 => '‚', 34 => 'ƒ', 35 => '„', 36 => '…', 37 => '†', 38 => '‡', 39 => 'ˆ', 40 => '‰', 41 => 'Š', 42 => '‹', 43 => 'Œ', 44 => '', 45 => 'Ž', 46 => '', 47 => '', 48 => '‘', 49 => '’', 50 => '“', 51 => '”', 52 => '•', 53 => '–', 54 => '—', 55 => '˜', 56 => '™', 57 => 'š', 58 => '›', 59 => 'œ', 60 => '', 61 => 'ž', 62 => 'Ÿ', 63 => ' ', 64 => '¡', 65 => '¢', 66 => '£', 67 => '¤', 68 => '¥', 69 => '¦', 70 => '§', 71 => '¨', 72 => '©', 73 => 'ª', 74 => '«', 75 => '¬', 76 => '­', 77 => '®', 78 => '¯', 79 => '°', 80 => '±', 81 => '²', 82 => '³', 83 => '´', 84 => 'µ', 85 => '¶', 86 => '·', 87 => '¸', 88 => '¹', 89 => 'º', 90 => '»', 91 => '¼', 92 => '½', 93 => '¾', 94 => '¿', 95 => 'À', 96 => 'Á', 97 => 'Â', 98 => 'Ã', 99 => 'Ä', 100 => 'Å', 101 => 'Æ', 102 => 'Ç', 103 => 'È', 104 => 'É', 105 => 'Ê', 106 => 'Ë', 107 => 'Ì', 108 => 'Í', 109 => 'Î', 110 => 'Ï', 111 => 'Ð', 112 => 'Ñ', 113 => 'Ò', 114 => 'Ó', 115 => 'Ô', 116 => 'Õ', 117 => 'Ö', 118 => '×', 119 => 'Ø', 120 => 'Ù', 121 => 'Ú', 122 => 'Û', 123 => 'Ü', 124 => 'Ý', 125 => 'Þ', 126 => 'ß', 127 => 'à', 128 => 'á', 129 => 'â', 130 => 'ã', 131 => 'ä', 132 => 'å', 133 => 'æ', 134 => 'ç', 135 => 'è', 136 => 'é', 137 => 'ê', 138 => 'ë', 139 => 'ì', 140 => 'í', 141 => 'î', 142 => 'ï', 143 => 'ð', 144 => 'ñ', 145 => 'ò', 146 => 'ó', 147 => 'ô', 148 => 'õ', 149 => 'ö', 150 => '÷', 151 => 'ø', 152 => 'ù', 153 => 'ú', 154 => 'û', 155 => 'ü', 156 => 'ý', 157 => 'þ', );

    /* 
     * replace illegal characters for escaped html character but don't touch anything else.  
     */
    public static function getSaveValue($value) {       
        return str_replace(self::$find, self::$replace, $value);
    }
    public static function makeIllegal($find,$replace) {
        self::$find[] = $find;
        self::$replace[] = $replace;
    }
}

This worked fine for me. If you have a string "Letters u00e1 u00e9 etc." replace by "Letters á é".

function unicode2html($str){
    // Set the locale to something that's UTF-8 capable
    setlocale(LC_ALL, 'en_US.UTF-8');
    // Convert the codepoints to entities
    $str = preg_replace("/u([0-9a-fA-F]{4})/", "&#x\\1;", $str);
    // Convert the entities to a UTF-8 string
    return iconv("UTF-8", "ISO-8859-1//TRANSLIT", $str);
}

With the aid of the following table:

http://en.wikipedia.org/wiki/UTF-8#Description

can't be simpler :)

Simply mask the unicode numbers according to which range they fit in.