printf ("0x%lX ", ord $buffer);

##</code><code>##

$ perl -E'say unpack "H*", "foobar"'
666f6f626172

##</code><code>##

$ perl -E'say "0x$_" for unpack "(H2)*", "foobar"'
0x66
0x6f
0x6f
0x62
0x61
0x72