Returns an uppercased version of EXPR. This is the internal function implementing the \U
escape in double-quoted strings. Respects current LC_CTYPE locale if use locale
in force. See perllocale. Under Unicode (use utf8
) it uses the standard Unicode uppercase mappings. (It does not attempt to do titlecase mapping on initial letters. See ucfirst
for that.)
If EXPR is omitted, uses $_
.