All of these are wrong. https://stackoverflow.com/a/35177899/308851 gets close but it gets Latin involved and gives no source for the rule either.
Let's check the standard... the library provided by the Unicode Consortium is ICU and the documentation has this to say:
For example, to remove accents from characters, use the following transform:
NFD; [:Nonspacing Mark:] Remove; NFC.
This transform separates accents from their base characters, removes the accents, and then puts the remaining text into an unaccented form.
That's it. No need for anything else.
Thus, if you have intl installed then you can do
$transliterator = Transliterator::createFromRules(':: NFD; :: [:Mn:] Remove; :: NFC;');
echo $transliterator->transliterate($string);
That's it. That's the answer to the question.
If you need to do this somewhere where intl is not available, you can snapshot what it does on a machine which does have intl:
<?php
$transliterator = \Transliterator::createFromRules(':: NFD; :: [:Mn:] Remove; :: NFC;');
$letters = preg_grep('/\pL/u', array_map('utf8', range(0x80, 0x2000)));
$letters = array_combine($letters, $letters);
$transliterated = array_map([$transliterator, 'transliterate'], $letters);
$map = array_diff_assoc($transliterated, $letters);
print count($map);
$search = [' => ', 'array (', ')', ' ', "\n"];
$replace = ['=>', '[', ']', '', ''];
$map = str_replace($search, $replace, var_export($map, TRUE));
file_put_contents("map.php", "<?php\n\$map = $map;");
function utf8($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 '';
}
?>
Here I have snapshotted the first 8192 characters which includes most non-Hiragana/Katakana scripts. The results are 9146 bytes long (Hiragana/Katakana more than doubles that and I didn't need it) encoding 827 replacements. You can put in your codebase and use it like this:
function removeAccents($string) {
include 'map.php';
return strtr($string, $map);
}
(this is demo, rather inline map.php into a class constant etc)
This is similar to https://stackoverflow.com/a/29280197/308851 but it includes a much larger number of characters -- and shows you how to obtain this mapping.
Ps.: Transliterating to ASCII is an entirely different bag of hurt. This is answer to "How do I remove accents from characters in a PHP string?"
Pps.: Here's the snapshot:
$map = ['À'=>'A','Á'=>'A','Â'=>'A','Ã'=>'A','Ä'=>'A','Å'=>'A','Ç'=>'C','È'=>'E','É'=>'E','Ê'=>'E','Ë'=>'E','Ì'=>'I','Í'=>'I','Î'=>'I','Ï'=>'I','Ñ'=>'N','Ò'=>'O','Ó'=>'O','Ô'=>'O','Õ'=>'O','Ö'=>'O','Ù'=>'U','Ú'=>'U','Û'=>'U','Ü'=>'U','Ý'=>'Y','à'=>'a','á'=>'a','â'=>'a','ã'=>'a','ä'=>'a','å'=>'a','ç'=>'c','è'=>'e','é'=>'e','ê'=>'e','ë'=>'e','ì'=>'i','í'=>'i','î'=>'i','ï'=>'i','ñ'=>'n','ò'=>'o','ó'=>'o','ô'=>'o','õ'=>'o','ö'=>'o','ù'=>'u','ú'=>'u','û'=>'u','ü'=>'u','ý'=>'y','ÿ'=>'y','Ā'=>'A','ā'=>'a','Ă'=>'A','ă'=>'a','Ą'=>'A','ą'=>'a','Ć'=>'C','ć'=>'c','Ĉ'=>'C','ĉ'=>'c','Ċ'=>'C','ċ'=>'c','Č'=>'C','č'=>'c','Ď'=>'D','ď'=>'d','Ē'=>'E','ē'=>'e','Ĕ'=>'E','ĕ'=>'e','Ė'=>'E','ė'=>'e','Ę'=>'E','ę'=>'e','Ě'=>'E','ě'=>'e','Ĝ'=>'G','ĝ'=>'g','Ğ'=>'G','ğ'=>'g','Ġ'=>'G','ġ'=>'g','Ģ'=>'G','ģ'=>'g','Ĥ'=>'H','ĥ'=>'h','Ĩ'=>'I','ĩ'=>'i','Ī'=>'I','ī'=>'i','Ĭ'=>'I','ĭ'=>'i','Į'=>'I','į'=>'i','İ'=>'I','Ĵ'=>'J','ĵ'=>'j','Ķ'=>'K','ķ'=>'k','Ĺ'=>'L','ĺ'=>'l','Ļ'=>'L','ļ'=>'l','Ľ'=>'L','ľ'=>'l','Ń'=>'N','ń'=>'n','Ņ'=>'N','ņ'=>'n','Ň'=>'N','ň'=>'n','Ō'=>'O','ō'=>'o','Ŏ'=>'O','ŏ'=>'o','Ő'=>'O','ő'=>'o','Ŕ'=>'R','ŕ'=>'r','Ŗ'=>'R','ŗ'=>'r','Ř'=>'R','ř'=>'r','Ś'=>'S','ś'=>'s','Ŝ'=>'S','ŝ'=>'s','Ş'=>'S','ş'=>'s','Š'=>'S','š'=>'s','Ţ'=>'T','ţ'=>'t','Ť'=>'T','ť'=>'t','Ũ'=>'U','ũ'=>'u','Ū'=>'U','ū'=>'u','Ŭ'=>'U','ŭ'=>'u','Ů'=>'U','ů'=>'u','Ű'=>'U','ű'=>'u','Ų'=>'U','ų'=>'u','Ŵ'=>'W','ŵ'=>'w','Ŷ'=>'Y','ŷ'=>'y','Ÿ'=>'Y','Ź'=>'Z','ź'=>'z','Ż'=>'Z','ż'=>'z','Ž'=>'Z','ž'=>'z','Ơ'=>'O','ơ'=>'o','Ư'=>'U','ư'=>'u','Ǎ'=>'A','ǎ'=>'a','Ǐ'=>'I','ǐ'=>'i','Ǒ'=>'O','ǒ'=>'o','Ǔ'=>'U','ǔ'=>'u','Ǖ'=>'U','ǖ'=>'u','Ǘ'=>'U','ǘ'=>'u','Ǚ'=>'U','ǚ'=>'u','Ǜ'=>'U','ǜ'=>'u','Ǟ'=>'A','ǟ'=>'a','Ǡ'=>'A','ǡ'=>'a','Ǣ'=>'Æ','ǣ'=>'æ','Ǧ'=>'G','ǧ'=>'g','Ǩ'=>'K','ǩ'=>'k','Ǫ'=>'O','ǫ'=>'o','Ǭ'=>'O','ǭ'=>'o','Ǯ'=>'Ʒ','ǯ'=>'ʒ','ǰ'=>'j','Ǵ'=>'G','ǵ'=>'g','Ǹ'=>'N','ǹ'=>'n','Ǻ'=>'A','ǻ'=>'a','Ǽ'=>'Æ','ǽ'=>'æ','Ǿ'=>'Ø','ǿ'=>'ø','Ȁ'=>'A','ȁ'=>'a','Ȃ'=>'A','ȃ'=>'a','Ȅ'=>'E','ȅ'=>'e','Ȇ'=>'E','ȇ'=>'e','Ȉ'=>'I','ȉ'=>'i','Ȋ'=>'I','ȋ'=>'i','Ȍ'=>'O','ȍ'=>'o','Ȏ'=>'O','ȏ'=>'o','Ȑ'=>'R','ȑ'=>'r','Ȓ'=>'R','ȓ'=>'r','Ȕ'=>'U','ȕ'=>'u','Ȗ'=>'U','ȗ'=>'u','Ș'=>'S','ș'=>'s','Ț'=>'T','ț'=>'t','Ȟ'=>'H','ȟ'=>'h','Ȧ'=>'A','ȧ'=>'a','Ȩ'=>'E','ȩ'=>'e','Ȫ'=>'O','ȫ'=>'o','Ȭ'=>'O','ȭ'=>'o','Ȯ'=>'O','ȯ'=>'o','Ȱ'=>'O','ȱ'=>'o','Ȳ'=>'Y','ȳ'=>'y','ʹ'=>'ʹ','Ά'=>'Α','Έ'=>'Ε','Ή'=>'Η','Ί'=>'Ι','Ό'=>'Ο','Ύ'=>'Υ','Ώ'=>'Ω','ΐ'=>'ι','Ϊ'=>'Ι','Ϋ'=>'Υ','ά'=>'α','έ'=>'ε','ή'=>'η','ί'=>'ι','ΰ'=>'υ','ϊ'=>'ι','ϋ'=>'υ','ό'=>'ο','ύ'=>'υ','ώ'=>'ω','ϓ'=>'ϒ','ϔ'=>'ϒ','Ѐ'=>'Е','Ё'=>'Е','Ѓ'=>'Г','Ї'=>'І','Ќ'=>'К','Ѝ'=>'И','Ў'=>'У','Й'=>'И','й'=>'и','ѐ'=>'е','ё'=>'е','ѓ'=>'г','ї'=>'і','ќ'=>'к','ѝ'=>'и','ў'=>'у','Ѷ'=>'Ѵ','ѷ'=>'ѵ','Ӂ'=>'Ж','ӂ'=>'ж','Ӑ'=>'А','ӑ'=>'а','Ӓ'=>'А','ӓ'=>'а','Ӗ'=>'Е','ӗ'=>'е','Ӛ'=>'Ә','ӛ'=>'ә','Ӝ'=>'Ж','ӝ'=>'ж','Ӟ'=>'З','ӟ'=>'з','Ӣ'=>'И','ӣ'=>'и','Ӥ'=>'И','ӥ'=>'и','Ӧ'=>'О','ӧ'=>'о','Ӫ'=>'Ө','ӫ'=>'ө','Ӭ'=>'Э','ӭ'=>'э','Ӯ'=>'У','ӯ'=>'у','Ӱ'=>'У','ӱ'=>'у','Ӳ'=>'У','ӳ'=>'у','Ӵ'=>'Ч','ӵ'=>'ч','Ӹ'=>'Ы','ӹ'=>'ы','آ'=>'ا','أ'=>'ا','ؤ'=>'و','إ'=>'ا','ئ'=>'ي','ۀ'=>'ە','ۂ'=>'ہ','ۓ'=>'ے','ऩ'=>'न','ऱ'=>'र','ऴ'=>'ळ','क़'=>'क','ख़'=>'ख','ग़'=>'ग','ज़'=>'ज','ड़'=>'ड','ढ़'=>'ढ','फ़'=>'फ','य़'=>'य','ড়'=>'ড','ঢ়'=>'ঢ','য়'=>'য','ਲ਼'=>'ਲ','ਸ਼'=>'ਸ','ਖ਼'=>'ਖ','ਗ਼'=>'ਗ','ਜ਼'=>'ਜ','ਫ਼'=>'ਫ','ଡ଼'=>'ଡ','ଢ଼'=>'ଢ','གྷ'=>'ག','ཌྷ'=>'ཌ','དྷ'=>'ད','བྷ'=>'བ','ཛྷ'=>'ཛ','ཀྵ'=>'ཀ','ဦ'=>'ဥ','Ḁ'=>'A','ḁ'=>'a','Ḃ'=>'B','ḃ'=>'b','Ḅ'=>'B','ḅ'=>'b','Ḇ'=>'B','ḇ'=>'b','Ḉ'=>'C','ḉ'=>'c','Ḋ'=>'D','ḋ'=>'d','Ḍ'=>'D','ḍ'=>'d','Ḏ'=>'D','ḏ'=>'d','Ḑ'=>'D','ḑ'=>'d','Ḓ'=>'D','ḓ'=>'d','Ḕ'=>'E','ḕ'=>'e','Ḗ'=>'E','ḗ'=>'e','Ḙ'=>'E','ḙ'=>'e','Ḛ'=>'E','ḛ'=>'e','Ḝ'=>'E','ḝ'=>'e','Ḟ'=>'F','ḟ'=>'f','Ḡ'=>'G','ḡ'=>'g','Ḣ'=>'H','ḣ'=>'h','Ḥ'=>'H','ḥ'=>'h','Ḧ'=>'H','ḧ'=>'h','Ḩ'=>'H','ḩ'=>'h','Ḫ'=>'H','ḫ'=>'h','Ḭ'=>'I','ḭ'=>'i','Ḯ'=>'I','ḯ'=>'i','Ḱ'=>'K','ḱ'=>'k','Ḳ'=>'K','ḳ'=>'k','Ḵ'=>'K','ḵ'=>'k','Ḷ'=>'L','ḷ'=>'l','Ḹ'=>'L','ḹ'=>'l','Ḻ'=>'L','ḻ'=>'l','Ḽ'=>'L','ḽ'=>'l','Ḿ'=>'M','ḿ'=>'m','Ṁ'=>'M','ṁ'=>'m','Ṃ'=>'M','ṃ'=>'m','Ṅ'=>'N','ṅ'=>'n','Ṇ'=>'N','ṇ'=>'n','Ṉ'=>'N','ṉ'=>'n','Ṋ'=>'N','ṋ'=>'n','Ṍ'=>'O','ṍ'=>'o','Ṏ'=>'O','ṏ'=>'o','Ṑ'=>'O','ṑ'=>'o','Ṓ'=>'O','ṓ'=>'o','Ṕ'=>'P','ṕ'=>'p','Ṗ'=>'P','ṗ'=>'p','Ṙ'=>'R','ṙ'=>'r','Ṛ'=>'R','ṛ'=>'r','Ṝ'=>'R','ṝ'=>'r','Ṟ'=>'R','ṟ'=>'r','Ṡ'=>'S','ṡ'=>'s','Ṣ'=>'S','ṣ'=>'s','Ṥ'=>'S','ṥ'=>'s','Ṧ'=>'S','ṧ'=>'s','Ṩ'=>'S','ṩ'=>'s','Ṫ'=>'T','ṫ'=>'t','Ṭ'=>'T','ṭ'=>'t','Ṯ'=>'T','ṯ'=>'t','Ṱ'=>'T','ṱ'=>'t','Ṳ'=>'U','ṳ'=>'u','Ṵ'=>'U','ṵ'=>'u','Ṷ'=>'U','ṷ'=>'u','Ṹ'=>'U','ṹ'=>'u','Ṻ'=>'U','ṻ'=>'u','Ṽ'=>'V','ṽ'=>'v','Ṿ'=>'V','ṿ'=>'v','Ẁ'=>'W','ẁ'=>'w','Ẃ'=>'W','ẃ'=>'w','Ẅ'=>'W','ẅ'=>'w','Ẇ'=>'W','ẇ'=>'w','Ẉ'=>'W','ẉ'=>'w','Ẋ'=>'X','ẋ'=>'x','Ẍ'=>'X','ẍ'=>'x','Ẏ'=>'Y','ẏ'=>'y','Ẑ'=>'Z','ẑ'=>'z','Ẓ'=>'Z','ẓ'=>'z','Ẕ'=>'Z','ẕ'=>'z','ẖ'=>'h','ẗ'=>'t','ẘ'=>'w','ẙ'=>'y','ẛ'=>'ſ','Ạ'=>'A','ạ'=>'a','Ả'=>'A','ả'=>'a','Ấ'=>'A','ấ'=>'a','Ầ'=>'A','ầ'=>'a','Ẩ'=>'A','ẩ'=>'a','Ẫ'=>'A','ẫ'=>'a','Ậ'=>'A','ậ'=>'a','Ắ'=>'A','ắ'=>'a','Ằ'=>'A','ằ'=>'a','Ẳ'=>'A','ẳ'=>'a','Ẵ'=>'A','ẵ'=>'a','Ặ'=>'A','ặ'=>'a','Ẹ'=>'E','ẹ'=>'e','Ẻ'=>'E','ẻ'=>'e','Ẽ'=>'E','ẽ'=>'e','Ế'=>'E','ế'=>'e','Ề'=>'E','ề'=>'e','Ể'=>'E','ể'=>'e','Ễ'=>'E','ễ'=>'e','Ệ'=>'E','ệ'=>'e','Ỉ'=>'I','ỉ'=>'i','Ị'=>'I','ị'=>'i','Ọ'=>'O','ọ'=>'o','Ỏ'=>'O','ỏ'=>'o','Ố'=>'O','ố'=>'o','Ồ'=>'O','ồ'=>'o','Ổ'=>'O','ổ'=>'o','Ỗ'=>'O','ỗ'=>'o','Ộ'=>'O','ộ'=>'o','Ớ'=>'O','ớ'=>'o','Ờ'=>'O','ờ'=>'o','Ở'=>'O','ở'=>'o','Ỡ'=>'O','ỡ'=>'o','Ợ'=>'O','ợ'=>'o','Ụ'=>'U','ụ'=>'u','Ủ'=>'U','ủ'=>'u','Ứ'=>'U','ứ'=>'u','Ừ'=>'U','ừ'=>'u','Ử'=>'U','ử'=>'u','Ữ'=>'U','ữ'=>'u','Ự'=>'U','ự'=>'u','Ỳ'=>'Y','ỳ'=>'y','Ỵ'=>'Y','ỵ'=>'y','Ỷ'=>'Y','ỷ'=>'y','Ỹ'=>'Y','ỹ'=>'y','ἀ'=>'α','ἁ'=>'α','ἂ'=>'α','ἃ'=>'α','ἄ'=>'α','ἅ'=>'α','ἆ'=>'α','ἇ'=>'α','Ἀ'=>'Α','Ἁ'=>'Α','Ἂ'=>'Α','Ἃ'=>'Α','Ἄ'=>'Α','Ἅ'=>'Α','Ἆ'=>'Α','Ἇ'=>'Α','ἐ'=>'ε','ἑ'=>'ε','ἒ'=>'ε','ἓ'=>'ε','ἔ'=>'ε','ἕ'=>'ε','Ἐ'=>'Ε','Ἑ'=>'Ε','Ἒ'=>'Ε','Ἓ'=>'Ε','Ἔ'=>'Ε','Ἕ'=>'Ε','ἠ'=>'η','ἡ'=>'η','ἢ'=>'η','ἣ'=>'η','ἤ'=>'η','ἥ'=>'η','ἦ'=>'η','ἧ'=>'η','Ἠ'=>'Η','Ἡ'=>'Η','Ἢ'=>'Η','Ἣ'=>'Η','Ἤ'=>'Η','Ἥ'=>'Η','Ἦ'=>'Η','Ἧ'=>'Η','ἰ'=>'ι','ἱ'=>'ι','ἲ'=>'ι','ἳ'=>'ι','ἴ'=>'ι','ἵ'=>'ι','ἶ'=>'ι','ἷ'=>'ι','Ἰ'=>'Ι','Ἱ'=>'Ι','Ἲ'=>'Ι','Ἳ'=>'Ι','Ἴ'=>'Ι','Ἵ'=>'Ι','Ἶ'=>'Ι','Ἷ'=>'Ι','ὀ'=>'ο','ὁ'=>'ο','ὂ'=>'ο','ὃ'=>'ο','ὄ'=>'ο','ὅ'=>'ο','Ὀ'=>'Ο','Ὁ'=>'Ο','Ὂ'=>'Ο','Ὃ'=>'Ο','Ὄ'=>'Ο','Ὅ'=>'Ο','ὐ'=>'υ','ὑ'=>'υ','ὒ'=>'υ','ὓ'=>'υ','ὔ'=>'υ','ὕ'=>'υ','ὖ'=>'υ','ὗ'=>'υ','Ὑ'=>'Υ','Ὓ'=>'Υ','Ὕ'=>'Υ','Ὗ'=>'Υ','ὠ'=>'ω','ὡ'=>'ω','ὢ'=>'ω','ὣ'=>'ω','ὤ'=>'ω','ὥ'=>'ω','ὦ'=>'ω','ὧ'=>'ω','Ὠ'=>'Ω','Ὡ'=>'Ω','Ὢ'=>'Ω','Ὣ'=>'Ω','Ὤ'=>'Ω','Ὥ'=>'Ω','Ὦ'=>'Ω','Ὧ'=>'Ω','ὰ'=>'α','ά'=>'α','ὲ'=>'ε','έ'=>'ε','ὴ'=>'η','ή'=>'η','ὶ'=>'ι','ί'=>'ι','ὸ'=>'ο','ό'=>'ο','ὺ'=>'υ','ύ'=>'υ','ὼ'=>'ω','ώ'=>'ω','ᾀ'=>'α','ᾁ'=>'α','ᾂ'=>'α','ᾃ'=>'α','ᾄ'=>'α','ᾅ'=>'α','ᾆ'=>'α','ᾇ'=>'α','ᾈ'=>'Α','ᾉ'=>'Α','ᾊ'=>'Α','ᾋ'=>'Α','ᾌ'=>'Α','ᾍ'=>'Α','ᾎ'=>'Α','ᾏ'=>'Α','ᾐ'=>'η','ᾑ'=>'η','ᾒ'=>'η','ᾓ'=>'η','ᾔ'=>'η','ᾕ'=>'η','ᾖ'=>'η','ᾗ'=>'η','ᾘ'=>'Η','ᾙ'=>'Η','ᾚ'=>'Η','ᾛ'=>'Η','ᾜ'=>'Η','ᾝ'=>'Η','ᾞ'=>'Η','ᾟ'=>'Η','ᾠ'=>'ω','ᾡ'=>'ω','ᾢ'=>'ω','ᾣ'=>'ω','ᾤ'=>'ω','ᾥ'=>'ω','ᾦ'=>'ω','ᾧ'=>'ω','ᾨ'=>'Ω','ᾩ'=>'Ω','ᾪ'=>'Ω','ᾫ'=>'Ω','ᾬ'=>'Ω','ᾭ'=>'Ω','ᾮ'=>'Ω','ᾯ'=>'Ω','ᾰ'=>'α','ᾱ'=>'α','ᾲ'=>'α','ᾳ'=>'α','ᾴ'=>'α','ᾶ'=>'α','ᾷ'=>'α','Ᾰ'=>'Α','Ᾱ'=>'Α','Ὰ'=>'Α','Ά'=>'Α','ᾼ'=>'Α','ι'=>'ι','ῂ'=>'η','ῃ'=>'η','ῄ'=>'η','ῆ'=>'η','ῇ'=>'η','Ὲ'=>'Ε','Έ'=>'Ε','Ὴ'=>'Η','Ή'=>'Η','ῌ'=>'Η','ῐ'=>'ι','ῑ'=>'ι','ῒ'=>'ι','ΐ'=>'ι','ῖ'=>'ι','ῗ'=>'ι','Ῐ'=>'Ι','Ῑ'=>'Ι','Ὶ'=>'Ι','Ί'=>'Ι','ῠ'=>'υ','ῡ'=>'υ','ῢ'=>'υ','ΰ'=>'υ','ῤ'=>'ρ','ῥ'=>'ρ','ῦ'=>'υ','ῧ'=>'υ','Ῠ'=>'Υ','Ῡ'=>'Υ','Ὺ'=>'Υ','Ύ'=>'Υ','Ῥ'=>'Ρ','ῲ'=>'ω','ῳ'=>'ω','ῴ'=>'ω','ῶ'=>'ω','ῷ'=>'ω','Ὸ'=>'Ο','Ό'=>'Ο','Ὼ'=>'Ω','Ώ'=>'Ω','ῼ'=>'Ω'];
