How to check if a string is uppercase?

Question

Perl

How to check if all characters of a string are in upper case?
if($str = all uppercase characters){
action
}

Answer 1

if ($str =~ /^[ \p{Uppercase}]+$/) {
    print "ВСЕ БУКВЫ БОЛЬШИЕ r\n";
}

Answer 2

if ( $str =~ /^[A-ZA-Z]+$/ )
this is, of course, if the locale is enabled and all that.