in reply to Flipping the Sign Bit in pack()'ed Value

You used strict. Very good. But you didn't use warnings. Why?

When I run the code with warnings, I'm getting 

Argument "B" isn't numeric in numeric bitwise xor (^) at 1.pl line 10.

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But even using 

use feature qw( bitwise );

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and changing the xor line to 
my $stoval = "$pckval" ^. 0x80;

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doesn't fix it according to your expectations: 
$stoval = "B" ^. 0x80;  # $stoval = [s28]  -  Expecting [194]
$stohex = "0x" . (unpack 'H16', "s28");  # $stohex = [0x733238]  -  Ex
+pecting [0xc2]

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You need to use a character on the right hand side of the xor, too. 

my $stoval = $pckval ^ "\x80";
# or
my $stoval = $pckval ^ chr 0x80;
# or
my $stoval = $pckval ^ pack 'C', 0x80;
# ...

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map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

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Re^2: Flipping the Sign Bit in pack()'ed Value
by marinersk (Priest) on Jun 09, 2025 at 13:30 UTC

    choroba wrote:

    You used strict. Very good. But you didn't use warnings. Why?

    Long list of reasons. Short answer: Bad habits, I was in a hurry, and I'm arrogant.

    And that bit me: May the lesson stick well this time

    You need to use a character on the right hand side of the xor, too.

    Thank you. (My instinct was suggesting a typecasting problem; I probably should have followed up on that before posting. Ah, well.)

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