First, the code you posted and the code you ran is actually different. There's only one byte in the string assigned to $test in the code you posted. There was two in the code you ran.

Second, you'll find Devel::Peek's Dump more useful at debugging this kind of problem. 

                                                   Internally
>perl -MDevel::Peek -e"Dump(qq{\x{C2AE}});"     __ encoded
SV = PV(0x23734c) at 0x235fc0                  /   as UTF-8
  REFCNT = 1                                  /
  FLAGS = (PADBUSY,PADTMP,POK,READONLY,pPOK,UTF8)
  PV = 0x182f574 "\354\212\256"\0 [UTF8 "\x{c2ae}"]
  CUR = 3         -----v------           ---v----
  LEN = 4               \                    \____ String
                         \
                          \_______________________ Internal
                                                   encoding
                                                   (bytes)
>perl -MDevel::Peek -e"Dump('abc');"
SV = PV(0x236e00) at 0x182f778
  REFCNT = 1
  FLAGS = (PADBUSY,PADTMP,POK,READONLY,pPOK)
  PV = 0x182f56c "abc"\0
  CUR = 3         -v-         Bytes treated as
  LEN = 4           \________ iso-latin-1 by
                              perl functions

[download]

Can anyone tell me why the following code:

It all boils down to the following: Until you tell it otherwise by using "use utf8;", perl treats source code as iso-latin-1. You created an UTF-8 source file, and failed to notify perl.

$test is assigned two bytes or two iso-latin-1 chars. (Same thing, the difference is in how its used.) Adding "use utf8;" before the constant will cause the constant to be decoded from UTF-8.

When you call encode('UTF-8'), you're encoding characters that you've never decoded, producing junk.

On a related note, what is the difference between:
$test = "\x{05D0}\x{20AC}";
and
$test = "\x05\xD0\x20\xAC";

The first is a string of two UNICODE characters (internally encoded as UTF-8).
The second is a string of four bytes or four iso-latin-1 characters. 

>perl -MDevel::Peek -e"Dump(qq{\x{05D0}\x{20AC}});"
SV = PV(0x237354) at 0x235fc8
  REFCNT = 1
  FLAGS = (PADBUSY,PADTMP,POK,READONLY,pPOK,UTF8)
  PV = 0x18307bc "\327\220\342\202\254"\0 [UTF8 "\x{5d0}\x{20ac}"]
  CUR = 5
  LEN = 8

>perl -MDevel::Peek -e"Dump(qq{\x05\xD0\x20\xAC});"
SV = PV(0x237354) at 0x235fc8
  REFCNT = 1
  FLAGS = (PADBUSY,PADTMP,POK,READONLY,pPOK)
  PV = 0x18307bc "\5\320 \254"\0
  CUR = 4
  LEN = 8

[download]

In reply to Re: UTF-8 representation question by ikegami
in thread UTF-8 representation question by bpa

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