Re^2: comparison of packed signed integers

I'm not sure that will work if negative numbers come into it.

knoppix@Microknoppix:~$ perl -E '
> $pos = pack q{N}, 10000;
> say unpack q{B*}, $pos;
> $neg = pack q{N}, -10000;
> say unpack q{B*}, $neg;
> say $pos gt $neg ? q{Good} : q{Bad};'
00000000000000000010011100010000
11111111111111111101100011110000
Bad
knoppix@Microknoppix:~$
[download]

You'd probably have to expand the tests to cater for that.

Cheers,

JohnGG

Comment on Re^2: comparison of packed signed integers Download Code

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Re^3: comparison of packed signed integers by BrowserUk (Patriarch) on Oct 30, 2011 at 12:00 UTC
pack template 'N' is for unsigned integers. If you need to cater for signed integers, you need template 'l>'. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^4: comparison of packed signed integers by johngg (Canon) on Oct 30, 2011 at 12:28 UTC
Yes, but the same holds true using 'l>'. `knoppix@Microknoppix:~$ perl -E ' > $pos = pack q{l>}, 10000; > say unpack q{B}, $pos; > $neg = pack q{l>}, -10000; > say unpack q{B}, $neg; > say $pos gt $neg ? q{Good} : q{Bad};' 00000000000000000010011100010000 11111111111111111101100011110000 Bad knoppix@Microknoppix:~$` [download] I think that packing with 'N' or 'l>' will always produce the same results, it is unpacking where it makes a difference. knoppix@Microknoppix:~$ perl -E ' > for ( -2147483648, -1, 0, 1, 2147483647, 4294967295 ) > { > say qq{$_:}; > say unpack q{B}, pack q{N}, $_; > say unpack q{B}, pack q{l>}, $_; > say q{-} x 32; > }; > ' -2147483648: 10000000000000000000000000000000 10000000000000000000000000000000 -------------------------------- -1: 11111111111111111111111111111111 11111111111111111111111111111111 -------------------------------- 0: 00000000000000000000000000000000 00000000000000000000000000000000 -------------------------------- 1: 00000000000000000000000000000001 00000000000000000000000000000001 -------------------------------- 2147483647: 01111111111111111111111111111111 01111111111111111111111111111111 -------------------------------- 4294967295: 11111111111111111111111111111111 11111111111111111111111111111111 -------------------------------- knoppix@Microknoppix:~$ [download] However, I'm happy to be corrected if I'm wrong. Cheers, JohnGG	[reply] [d/l] [select]
Re^5: comparison of packed signed integers by BrowserUk (Patriarch) on Oct 30, 2011 at 12:33 UTC
However, I'm happy to be corrected if I'm wrong. You're not wrong! Thanks for the reality check. It will only work with unsigned big-endian. I'll update my post above. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]