in reply to Re^2: How to determine if string contains non-ASCII characters ?
in thread How to determine if string contains non-ASCII characters ?

Your solution checks if any characters aren't ASCII.

my $is_ascii = $string !~ /[^\x00-\x7F]/;

An alternative is to check that all characters are ASCII.

my $is_ascii = $string =~ /^[\x00-\x7F]*\z/;

Both are fine. The first can be faster if the result is false, but the difference is probably inconsequential in practice.