perl encoding

##测试 撰写本文时，还没搞好我需要的东西，本文作为记录

在介绍处理 encoding 中，我发现perl有4种方法处理encoding;

[ commandline ] ( http://perldoc.perl.org/perlrun.html#%2A-C-%5B%5Fnumber/list%5F%5D%2A )

perl -CSDL -le 'print "\x{1815}"';

[ binmode ] ( http://perldoc.perl.org/functions/binmode.html )

binmode(STDOUT, ":utf8");          #treat as if it is UTF-8
binmode(STDIN, ":encoding(utf8)"); #actually check if it is UTF-8

[ PerlIO ] ( http://perldoc.perl.org/PerlIO.html )

open my $fh, ">:utf8", $filename
    or die "could not open $filename: $!\n";

open my $fh, "<:encoding(utf-8)", $filename
    or die "could not open $filename: $!\n";

[ open pragma ] ( http://perldoc.perl.org/open.html )

use open ":encoding(utf8)";
use open IN => ":encoding(utf8)", OUT => ":utf8";