It *looks* like if I use chr(???) with a ??? <= 255 I will always get the single byte I am looking for (i.e. not translated to/from some type of unicode symbol set). Correct ?
Well... in a way... yes. But you're overlooking one thing: if Perl concatenates a UTF8 string with a Latin-1 string (at least, that's the only way to think about it that makes sense), Perl will convert the Latin-1 string to UTF-8. Let me show you with an example: 
($\, $,) = ("\n", " "); # set up output mode
$string = "A" . chr(180) . "B";  # Latin-1
print unpack "C*", $string;
$string .= chr(367); # UTF-8
print unpack "C*", $string;

[download]
Output: 
65 180 66
65 194 180 66 197 175
As you can see, the original chr(180), between chr(65) ("A") and chr(66) ("B") is converted to UTF-8, rsulting in two bytes.

So, if you want UTF-8, all you have to do is insert the characters into a UTF-8 string, or concatenate it with a UTF-8 string. That may even be a zero-length string, asq returned by pack "U0": 

($\, $,) = ("\n", " "); # set up output mode
$string = "A" . chr(180) . "B";  # Latin-1
print unpack "C*", $string;
$string .= pack "U0"; # zero length, UTF-8
print unpack "C*", $string;

[download]
Result: 
65 180 66
65 194 180 66

p.s. This was tested with perl 5.6.1. on Windows. Not that it matters much — it shouldn't, except that you need at least perl 5.6.

In reply to Re: Re: Re: Why is variable interpolation suppressed in \x{$xxx} replacement ? by bart
in thread Why is variable interpolation suppressed in \x{$xxx} replacement ? by Anonymous Monk

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