Bug #77555 [Opn->Dup]: Why does mb_strtoupper change 'ß' to 'ss' in words like 'groß'?

Edit report at https://bugs.php.net/bug.php?id=77555&edit=1 ID: 77555 Updated by: nikic@php.net Reported by: dirk dot gerigk at atraveo dot com Summary: Why does mb_strtoupper change 'ß' to 'ss' in words like 'groß'? -Status: Open +Status: Duplicate Type: Bug Package: *Unicode Issues Operating System: Windows 10 PHP Version: 7.3.1 Block user comment: N Private report: N New Comment: Duplicate of bug #76696. Previous Comments: ------------------------------------------------------------------------ [2019-02-01 10:29:30] dirk dot gerigk at atraveo dot com Description: ------------ I try to understand why this was implemented. When you do print mb_strtolower("Groẞ"); it becomes 'groß' UPPER CASE ẞ becomes LOWER CASE ß print mb_strtolower("Groß"); will be 'groß' LOWER CASE ß unchanged print mb_strupper("groẞ"); will be 'GROẞ' UPPER CASE ẞ stays unchanged! But print mb_strtoupper("groß"); becomes 'GROSS' Why does it not become UPPER CASE ẞ? Not all words in german can be changed in that way and should only changed if needed. UPPER CASE ẞ is offical see https://en.wikipedia.org/wiki/Capital_%E1%BA%9E Test script: --------------- print mb_strtoupper("groß"); Expected result: ---------------- GROẞ Actual result: -------------- GROSS ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=77555&edit=1