Multibyte strings and weird error

Question

Why does the following code behave differently for different multibyte strings?

echo preg_replace('@(?=\pL)@u', '*', 'م'); // prints: '*م' ✓ echo preg_replace('@(?=\pL)@u', '*', 'ض'); // prints: '*ض' ✓ echo preg_replace('@(?=\pL)@u', '*', 'غ'); // prints: '* * ' ✗ echo preg_replace('@(?=\pL)@u', '*', 'ص'); // prints: '* * ' ✗ 

See: http://3v4l.org/fvab1

Answer 1

You also need to enter modifier letters ( Lm ). See the following iteration script for the entire Arabic Unicode block:

 <?php function uchar_2($dec) { $utf = chr(192 + (($dec - ($dec % 64)) / 64)); $utf .= chr(128 + ($dec % 64)); return $utf; } $issues = 0; $count = 0; for ($dec = 1536; $dec <= 1791; $dec++) { $char = uchar_2($dec); if (preg_replace('@^(?=\pLm) $@u ', '*', $char) !== $char) { printf("Issue with %s (%s)\n", $dec, $char); $issues++; } $count++; } printf("Found %d issues in %d rows\n", $issues, $count); 

Without Lm this will result in an error for about half the characters.