How to handle diacritics (accents) when rewriting 'pretty URLs'
Ultimately, you're going to have to give up on the idea of "correct", for this problem. Translating the string, no matter how you do it, destroys accuracy in the name of compatibility and readability. All three options are equally compatible, but #1 and #2 suffer in terms of readability. So just run with it and go for whatever looks best — option #3.
Yes, the translations are wrong for German, but unless you start requiring your users to specify what language their titles are in (and restricting them to only one), you're not going to solve that problem without far more effort than it's worth. (For example, running each word in the title through dictionaries for each known language and translating that word's diacritics according to the rules of its language would work, but it's excessive.)
Alternatively, if German is a higher concern than other languages, make your translation always use the German version when one exists: ä→ae, ë→e, ï→i, ö→oe, ü→ue.
Edit:
Oh, and as for the actual method, I'd translate the special cases, if any, via str_replace, then use iconv for the rest:
$text = str_replace(array("ä", "ö", "ü", "ß"), array("ae", "oe", "ue", "ss"), $text);
$text = iconv('UTF-8', 'US-ASCII//TRANSLIT', $text);
Should I use accented characters in URLs?
When faced with a similar problem, I took advantage of URL rewriting to allow such pages to be accessible by either the accented or unaccented character. The actual URL would be something like
http://www.mysite.com/myresume.html
And a rewriting+character translating function allows this reference
http://www.mysite.com/myresumé.html
to load the same resource. So to answer your question, as the primary resource identifier, I confine myself to 0-9, A-Z, a-z and the occasional hyphen.
PHP: URL friendly strings
You can use iconv for the string replacement...
$string = iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $string);
Basically, it'll transliterate the characters it can, and drop those it can't (that are not in the ASCII character set)...
Then, just replace the spaces with str_replace:
$string = str_replace(' ', '-', $string);
Or, if you want to get fancy, you can replace all consecutive white-space characters with a single dash using a simple regex:
$string = preg_replace('/\\s+/', '-', $string);
Edit As @Robert Ros points out, you need to set the locale prior to using iconv (Depending on the defaults of your system). Just execute this line prior to the iconv line:
setlocale(LC_CTYPE, 'en_US.UTF8');
What char should I use to replace illegal characters in a url slug
Just use - for space and get rid of the illegal chars (like this site is).
Also it's all lower-case.
How do I remove diacritics (accents) from a string in .NET?
I've not used this method, but Michael Kaplan describes a method for doing so in his blog post (with a confusing title) that talks about stripping diacritics: Stripping is an interesting job (aka
On the meaning of meaningless, aka All
Mn characters are non-spacing, but
some are more non-spacing than
others)
static string RemoveDiacritics(string text)
{
var normalizedString = text.Normalize(NormalizationForm.FormD);
var stringBuilder = new StringBuilder(capacity: normalizedString.Length);
for (int i = 0; i < normalizedString.Length; i++)
{
char c = normalizedString[i];
var unicodeCategory = CharUnicodeInfo.GetUnicodeCategory(c);
if (unicodeCategory != UnicodeCategory.NonSpacingMark)
{
stringBuilder.Append(c);
}
}
return stringBuilder
.ToString()
.Normalize(NormalizationForm.FormC);
}
Note that this is a followup to his earlier post: Stripping diacritics....
The approach uses String.Normalize to split the input string into constituent glyphs (basically separating the "base" characters from the diacritics) and then scans the result and retains only the base characters. It's just a little complicated, but really you're looking at a complicated problem.
Of course, if you're limiting yourself to French, you could probably get away with the simple table-based approach in How to remove accents and tilde in a C++ std::string, as recommended by @David Dibben.
What char should I use to replace illegal characters in a url slug
Just use - for space and get rid of the illegal chars (like this site is).
Also it's all lower-case.
Remove diacritics from a string
There is a function that Wordpress uses and works nice. Here's the working code with output.
<?php
function seems_utf8($str)
{
$length = strlen($str);
for ($i=0; $i < $length; $i++) {
$c = ord($str[$i]);
if ($c < 0x80) $n = 0; # 0bbbbbbb
elseif (($c & 0xE0) == 0xC0) $n=1; # 110bbbbb
elseif (($c & 0xF0) == 0xE0) $n=2; # 1110bbbb
elseif (($c & 0xF8) == 0xF0) $n=3; # 11110bbb
elseif (($c & 0xFC) == 0xF8) $n=4; # 111110bb
elseif (($c & 0xFE) == 0xFC) $n=5; # 1111110b
else return false; # Does not match any model
for ($j=0; $j<$n; $j++) { # n bytes matching 10bbbbbb follow ?
if ((++$i == $length) || ((ord($str[$i]) & 0xC0) != 0x80))
return false;
}
}
return true;
}
/**
* Converts all accent characters to ASCII characters.
*
* If there are no accent characters, then the string given is just returned.
*
* @param string $string Text that might have accent characters
* @return string Filtered string with replaced "nice" characters.
*/
function remove_accents($string) {
if ( !preg_match('/[\x80-\xff]/', $string) )
return $string;
if (seems_utf8($string)) {
$chars = array(
// Decompositions for Latin-1 Supplement
chr(195).chr(128) => 'A', chr(195).chr(129) => 'A',
chr(195).chr(130) => 'A', chr(195).chr(131) => 'A',
chr(195).chr(132) => 'A', chr(195).chr(133) => 'A',
chr(195).chr(135) => 'C', chr(195).chr(136) => 'E',
chr(195).chr(137) => 'E', chr(195).chr(138) => 'E',
chr(195).chr(139) => 'E', chr(195).chr(140) => 'I',
chr(195).chr(141) => 'I', chr(195).chr(142) => 'I',
chr(195).chr(143) => 'I', chr(195).chr(145) => 'N',
chr(195).chr(146) => 'O', chr(195).chr(147) => 'O',
chr(195).chr(148) => 'O', chr(195).chr(149) => 'O',
chr(195).chr(150) => 'O', chr(195).chr(153) => 'U',
chr(195).chr(154) => 'U', chr(195).chr(155) => 'U',
chr(195).chr(156) => 'U', chr(195).chr(157) => 'Y',
chr(195).chr(159) => 's', chr(195).chr(160) => 'a',
chr(195).chr(161) => 'a', chr(195).chr(162) => 'a',
chr(195).chr(163) => 'a', chr(195).chr(164) => 'a',
chr(195).chr(165) => 'a', chr(195).chr(167) => 'c',
chr(195).chr(168) => 'e', chr(195).chr(169) => 'e',
chr(195).chr(170) => 'e', chr(195).chr(171) => 'e',
chr(195).chr(172) => 'i', chr(195).chr(173) => 'i',
chr(195).chr(174) => 'i', chr(195).chr(175) => 'i',
chr(195).chr(177) => 'n', chr(195).chr(178) => 'o',
chr(195).chr(179) => 'o', chr(195).chr(180) => 'o',
chr(195).chr(181) => 'o', chr(195).chr(182) => 'o',
chr(195).chr(182) => 'o', chr(195).chr(185) => 'u',
chr(195).chr(186) => 'u', chr(195).chr(187) => 'u',
chr(195).chr(188) => 'u', chr(195).chr(189) => 'y',
chr(195).chr(191) => 'y',
// Decompositions for Latin Extended-A
chr(196).chr(128) => 'A', chr(196).chr(129) => 'a',
chr(196).chr(130) => 'A', chr(196).chr(131) => 'a',
chr(196).chr(132) => 'A', chr(196).chr(133) => 'a',
chr(196).chr(134) => 'C', chr(196).chr(135) => 'c',
chr(196).chr(136) => 'C', chr(196).chr(137) => 'c',
chr(196).chr(138) => 'C', chr(196).chr(139) => 'c',
chr(196).chr(140) => 'C', chr(196).chr(141) => 'c',
chr(196).chr(142) => 'D', chr(196).chr(143) => 'd',
chr(196).chr(144) => 'D', chr(196).chr(145) => 'd',
chr(196).chr(146) => 'E', chr(196).chr(147) => 'e',
chr(196).chr(148) => 'E', chr(196).chr(149) => 'e',
chr(196).chr(150) => 'E', chr(196).chr(151) => 'e',
chr(196).chr(152) => 'E', chr(196).chr(153) => 'e',
chr(196).chr(154) => 'E', chr(196).chr(155) => 'e',
chr(196).chr(156) => 'G', chr(196).chr(157) => 'g',
chr(196).chr(158) => 'G', chr(196).chr(159) => 'g',
chr(196).chr(160) => 'G', chr(196).chr(161) => 'g',
chr(196).chr(162) => 'G', chr(196).chr(163) => 'g',
chr(196).chr(164) => 'H', chr(196).chr(165) => 'h',
chr(196).chr(166) => 'H', chr(196).chr(167) => 'h',
chr(196).chr(168) => 'I', chr(196).chr(169) => 'i',
chr(196).chr(170) => 'I', chr(196).chr(171) => 'i',
chr(196).chr(172) => 'I', chr(196).chr(173) => 'i',
chr(196).chr(174) => 'I', chr(196).chr(175) => 'i',
chr(196).chr(176) => 'I', chr(196).chr(177) => 'i',
chr(196).chr(178) => 'IJ',chr(196).chr(179) => 'ij',
chr(196).chr(180) => 'J', chr(196).chr(181) => 'j',
chr(196).chr(182) => 'K', chr(196).chr(183) => 'k',
chr(196).chr(184) => 'k', chr(196).chr(185) => 'L',
chr(196).chr(186) => 'l', chr(196).chr(187) => 'L',
chr(196).chr(188) => 'l', chr(196).chr(189) => 'L',
chr(196).chr(190) => 'l', chr(196).chr(191) => 'L',
chr(197).chr(128) => 'l', chr(197).chr(129) => 'L',
chr(197).chr(130) => 'l', chr(197).chr(131) => 'N',
chr(197).chr(132) => 'n', chr(197).chr(133) => 'N',
chr(197).chr(134) => 'n', chr(197).chr(135) => 'N',
chr(197).chr(136) => 'n', chr(197).chr(137) => 'N',
chr(197).chr(138) => 'n', chr(197).chr(139) => 'N',
chr(197).chr(140) => 'O', chr(197).chr(141) => 'o',
chr(197).chr(142) => 'O', chr(197).chr(143) => 'o',
chr(197).chr(144) => 'O', chr(197).chr(145) => 'o',
chr(197).chr(146) => 'OE',chr(197).chr(147) => 'oe',
chr(197).chr(148) => 'R',chr(197).chr(149) => 'r',
chr(197).chr(150) => 'R',chr(197).chr(151) => 'r',
chr(197).chr(152) => 'R',chr(197).chr(153) => 'r',
chr(197).chr(154) => 'S',chr(197).chr(155) => 's',
chr(197).chr(156) => 'S',chr(197).chr(157) => 's',
chr(197).chr(158) => 'S',chr(197).chr(159) => 's',
chr(197).chr(160) => 'S', chr(197).chr(161) => 's',
chr(197).chr(162) => 'T', chr(197).chr(163) => 't',
chr(197).chr(164) => 'T', chr(197).chr(165) => 't',
chr(197).chr(166) => 'T', chr(197).chr(167) => 't',
chr(197).chr(168) => 'U', chr(197).chr(169) => 'u',
chr(197).chr(170) => 'U', chr(197).chr(171) => 'u',
chr(197).chr(172) => 'U', chr(197).chr(173) => 'u',
chr(197).chr(174) => 'U', chr(197).chr(175) => 'u',
chr(197).chr(176) => 'U', chr(197).chr(177) => 'u',
chr(197).chr(178) => 'U', chr(197).chr(179) => 'u',
chr(197).chr(180) => 'W', chr(197).chr(181) => 'w',
chr(197).chr(182) => 'Y', chr(197).chr(183) => 'y',
chr(197).chr(184) => 'Y', chr(197).chr(185) => 'Z',
chr(197).chr(186) => 'z', chr(197).chr(187) => 'Z',
chr(197).chr(188) => 'z', chr(197).chr(189) => 'Z',
chr(197).chr(190) => 'z', chr(197).chr(191) => 's',
// Euro Sign
chr(226).chr(130).chr(172) => 'E',
// GBP (Pound) Sign
chr(194).chr(163) => '');
$string = strtr($string, $chars);
} else {
// Assume ISO-8859-1 if not UTF-8
$chars['in'] = chr(128).chr(131).chr(138).chr(142).chr(154).chr(158)
.chr(159).chr(162).chr(165).chr(181).chr(192).chr(193).chr(194)
.chr(195).chr(196).chr(197).chr(199).chr(200).chr(201).chr(202)
.chr(203).chr(204).chr(205).chr(206).chr(207).chr(209).chr(210)
.chr(211).chr(212).chr(213).chr(214).chr(216).chr(217).chr(218)
.chr(219).chr(220).chr(221).chr(224).chr(225).chr(226).chr(227)
.chr(228).chr(229).chr(231).chr(232).chr(233).chr(234).chr(235)
.chr(236).chr(237).chr(238).chr(239).chr(241).chr(242).chr(243)
.chr(244).chr(245).chr(246).chr(248).chr(249).chr(250).chr(251)
.chr(252).chr(253).chr(255);
$chars['out'] = "EfSZszYcYuAAAAAACEEEEIIIINOOOOOOUUUUYaaaaaaceeeeiiiinoooooouuuuyy";
$string = strtr($string, $chars['in'], $chars['out']);
$double_chars['in'] = array(chr(140), chr(156), chr(198), chr(208), chr(222), chr(223), chr(230), chr(240), chr(254));
$double_chars['out'] = array('OE', 'oe', 'AE', 'DH', 'TH', 'ss', 'ae', 'dh', 'th');
$string = str_replace($double_chars['in'], $double_chars['out'], $string);
}
return $string;
}
$str = "ľ š č ť ž ý á í é Č Á Ž Ý";
echo remove_accents($str); // Output: l s c t z y a i e C A Z Y
?>
Make exception when replacing diacritics with regular characters
The only simple way I see is not optimized but do the job properly :
const text = "Çééé éÇé àç" // test this string
.replace(/\u00e7/g, '__minC__') // save wanted chars position
.replace(/\u00c7/g, '__majC__')
.normalize('NFD') // normalize to prepare diacritic edit
.replace(/\p{Diacritic}/gu, '') // replace all diacritics
.replace(/__minC__/g, 'ç') // restore wanted chars
.replace(/__majC__/g, 'Ç')
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