in reply to How do unpack templates work

Try:

my( $bit1, $bit2 ) = unpack 'a4 a*', $uuid;

[download]

But, regarding your "more efficient than substr" remarks. For the sake of a single operation like this, you won't notice the difference; even if there actually is any.

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.

The start of some sanity?

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Re^2: How do unpack templates work
by unlinker (Monk) on Jul 20, 2012 at 19:06 UTC

    Yes - that works! Thanks.

    I agree that the efficiency/speed argument is not particularly compelling in this case. But a single unpack (when written correctly ;) ) is way more elegant that a bunch of substr calls

    Will wait for a later day to better understand why 'C' does not work

[reply]
      Will wait for a later day to better understand why 'C' does not work

      Don't wait. Try a few simple tests:

      print unpack 'H*', $uuid;;
767adecd8ed2e11191f4b1907aa0b7e4

print unpack 'a4', $uuid;;
vzÌ═

print unpack 'C4', $uuid;;
118 122 222 205

      [download]

      Look up what the 'C' template does. (Hint: see also ord ).

      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.

      The start of some sanity?
[reply]
[d/l]

        The first snippet is clear. So is the second, which I verified, extracts the first 4 bytes into a single variable. I do not understand your output in this case 'vzI&#..'

        Your example now makes the C template clear - it works differently in the sense that the number that follows the C is the number of octets to extract rather than number of octets to combine into a single variable.

        I missed this in the docs, if it is mentioned there. Is this behaviour unique to C? Again I could not find it in the docs. If you used the docs to figure this out, I would appreciate a pointer to the section

[reply]

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