Recognizing text as Simplified vs. Traditional Chi

Question

Given a block of text that's known to be Chinese and encoded in UTF-8, is there a way to determine if it's Simplified or Traditional?

Answer 1

Since big5 and gb2312 omit quite a few commonly used variants that are present in Unicode, the code rely on exact match between the translit and ignore modes would fail in quite a lot of normal use cases: it would fail to identify 説話 as Traditional Chinese despite 説 being a common variant in Hong Kong for 說 which is used in big5.

A simple fix is to do it in a fuzzy way:

$test1 = iconv("UTF-8", "big5//IGNORE", $text);
$test2 = iconv("UTF-8", "gb2312//IGNORE", $text);
$len1 = mb_strlen($test1);
$len2 = mb_strlen($test2);
$len0 = mb_strlen($text) * 0.8; // threshold
if ($len1 > $len2 && $len1 > $len0) {
    return 'Likely Traditional';
}
if ($len2 > $len1 && $len2 > $len0) {
    return 'Likely Simplified';
}
return 'Could not identify';

Answer 2

I don't know if this will work, but I'd try using iconv to see if it will translate between the charsets correctly, comparing the results from the same conversion with //TRANSLIT and //IGNORE. If the two results match, then the charset conversion hasn't encountered any characters that fail to translate, so you should have a match.

$test1 = iconv("UTF-8", "big5//TRANSLIT", $text);
$test2 = iconv("UTF-8", "big5//IGNORE", $text);
if ($test1 == $test2) {
   echo 'traditional';
} else {
   $test3 = iconv("UTF-8", "gb2312//TRANSLIT", $text);
   $test4 = iconv("UTF-8", "gb2312//IGNORE", $text);
   if ($test3 == $test4) {
      echo 'simplified';
   } else {
      echo 'Failed to match either traditional or simplified';
   }
}