Programming Perl, 4th Edition

reverse

reverse LIST

In list context, this function returns a list value consisting of the elements of LIST in the opposite order. The function can be used to create descending sequences:

for (reverse 1 .. 10) { ... }

Because of the way hashes flatten into lists when passed as a LIST, reverse can also be used to invert a hash, presuming the values are unique:

%barfoo = reverse %foobar;

In scalar context, the function concatenates all the elements of LIST and then returns the reverse of that resulting string, character by character. By character we mean codepoint, not grapheme. That means you will inappropriately reverse the pieces of “\r\n” into “\n\r”, causing combining characters to accidentally apply to the wrong base character. To do a reverse on graphemes instead of by codepoint, do this:

$codeuni = join "" => reverse $unicode =~ /\X/g;

A small hint: reversing a list sorted earlier by a user-defined function can often be achieved more easily by sorting the list in the opposite direction in the first place.