perl - How to print utf8 code points for each byte - perl

Question

I'm trying to print the code points for all possible byte values.
My test file :
$ perl -e ' open($fh,">raw_bytes.dat");while($i++<256){ print $fh chr($i-1) } close($fh)'
$ ls -l raw_bytes.dat
-rw-rw-r--+ 1 uuuuu Domain Users 256 Mar 20 15:41 raw_bytes.dat
$
What should go into the below #---> part so that I print the code points of utf8 $x in hexadecimal?
perl -e ' use utf8; open($fh,"<raw_bytes.dat");binmode($fh);
while($rb=read($fh,$x,1)) { utf8::encode($x);
#--->
} '
I tried %02x using printf, but it didn't work. Also, I want the solution only using core modules.

Answer 1

Use unpack('H*'):
$ perl -e '$x="\x80"; utf8::encode($x); print unpack("H*", $x), "\n"'
c280
For your example file I get
$ perl -e 'open($fh, "<", "raw_bytes.dat"); binmode($fh);
while ($rb=read($fh,$x,1)) { utf8::encode($x);
print unpack("H*", $x), "\n";
}'
00
01
02
03
...
7f
c280
c281
c282
c283
...
c3bd
c3be
c3bf
Variants:
$ perl -e '$x="\x80"; utf8::encode($x);
print uc(unpack("H*", $x)), "\n"'
C280
$ perl -e '$x="\x80"; utf8::encode($x);
($r = uc(unpack("H*", $x))) =~ s/(..)/\\X\1/g;
print "$r\n"'
\XC2\X80
# a little bit pointless example, but assume that $x is a provided Perl scalar....
$ perl -e '$x="\N{U+0080}\N{U+0081}";
printf("U+%04x ", ord($_)) foreach(split(//, $x));
print "\n";'
U+0080 U+0081
Please remember the difference between
a scalar holding a raw string: split(//) returns octets, e.g. \x80
a scalar holding a properly encoded string: split(//) returns characters, e.g. \N{U+0080}

Answer 2

I tried %02x using printf, but it didn't work.
You can use
printf "%vX\n", $x;
According to perldoc sprintf:
vector flag
This flag tells Perl to interpret the supplied string as a vector of
integers, one for each character in the string. Perl applies the
format to each integer in turn, then joins the resulting strings with
a separator (a dot . by default). This can be useful for displaying
ordinal values of characters in arbitrary strings.