BrowserUk has asked for the wisdom of the Perl Monks concerning the following question:
The description of the 'a', 'A' & 'Z' templates for pack reads:
a A string with arbitrary binary data, will be null padded. A A text (ASCII) string, will be space padded. Z A null-terminated (ASCIZ) string, will be null padded.
And sure enough:
print length pack '(A2)*', 'fr','ed','x';; 6 print unpack 'C*', pack '(A2)*', 'fr','ed','x';; 102 114 101 100 120 32 print length pack '(a2)*', 'fr','ed','x';; 6 print unpack 'C*', pack '(a2)*', 'fr','ed','x';; 102 114 101 100 120 0 print length pack '(Z2)*', 'fr','ed','x';; 6 print unpack 'C*', pack '(Z2)*', 'fr','ed','x';; 102 0 101 0 120 0 ## Note! the 'r' & 'd' characters have been thrown +away? Another bug?
And the docs for unpack say:
unpack does the reverse of pack: it takes a string and expands it out into a list of values.
But:
printf "'%s'\n", join"'", unpack '(A2)*', 'fredx';; 'fr'ed'x' printf "'%s'\n", join"'", unpack '(a2)*', 'fredx';; 'fr'ed'x' printf "'%s'\n", join"'", unpack '(Z2)*', 'fredx';; 'fr'ed'x'
Shouldn't that last element from unpack ('x') be padded with either space or null?
Has it always been 'wrong'? Is it too late to change it?
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".
I'm with torvalds on this
In the absence of evidence, opinion is indistinguishable from prejudice. Agile (and TDD) debunked
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Replies are listed 'Best First'. | |
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Re: pack() v unpack() padding: bug or ???
by Athanasius (Archbishop) on Feb 16, 2015 at 16:11 UTC | |
by BrowserUk (Patriarch) on Feb 16, 2015 at 16:32 UTC | |
by roboticus (Chancellor) on Feb 16, 2015 at 16:43 UTC | |
by BrowserUk (Patriarch) on Feb 16, 2015 at 17:06 UTC | |
Re: pack() v unpack() padding: bug or ???
by Anonymous Monk on Feb 16, 2015 at 13:57 UTC | |
by tye (Sage) on Feb 16, 2015 at 19:23 UTC | |
Re: pack() v unpack() padding: bug or ???
by GotToBTru (Prior) on Feb 16, 2015 at 16:02 UTC | |
by BrowserUk (Patriarch) on Feb 16, 2015 at 16:52 UTC |
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