How does Perl's length() function counts unicode characters?

Question

Why length() says this is 4 logical characters (I would expect it to say 1):

$ perl -lwe 'print length("🐪")'
4

I guess something is wrong with my expectation. :-) What is it?

Answer 1

Unless you tell Perl that the source code of the script is in utf8 Perl assumes ASCII. This means that by default the Perl interpreter sees 🐪 as 4 separate characters. If you change your one liner to perl -Mutf8 -lwe 'print length("🐪")' You see length providing your expected output.

The utf8 pragma tells Perl that the source unit is in utf8 and not ASCII. See perldoc utf8 for more info.