well... In my understanding it's just unclear what is the behaviour
when used with unpack().
If you look later in the pack manual you can read :
$baz = pack('s.l', 12, 4, 34);
# short 12, zero fill to position 4, long 34
this is exactly what stated in the manual, it null-fills up to
absolute position (in that case it will fill 2 bytes with zero)
so if you hexdump $baz it will contain (assuming a big-endian system):
00 0c 00 00 00 00 00 22
(on a little endian it would be 0c 00 00 00 22 00 00 00)
It's kind-of a surprising behaviour the one experienced when used with
unpack()...
but perhaps I just don't understand what the documentation mean with
'truncate'.
Cheers,
Andrea.
On Apr 22, 2009, at 7:40 PM, Ben Morrow wrote:
Quoth leon...@leonerd.org.uk (Paul LeoNerd Evans):
-=-=-=-=-=-
On Wed, Apr 22, 2009 at 02:10:03AM +0100, Ben Morrow wrote:
What am I missing here? It appears to me unpacking "." gives the
current
byte position in the string, which is what is needed.
~% perl -E'my $bin = pack "NN", 10, 12; say for unpack ".N.N.",
$bin'
0
10
4
12
8
Ah, youknow, that is exactly what I wanted :)
I had in fact looked up and down the docs for a format which would do
something like that, and didn't find it. Is that documented anywhere?
I've just sat and reread perldoc -f pack and perldoc -f unpack
_again_
and still haven't spotted it.
It appears (see Peter's reply) that it is only implemented in 5.10.
5.10's perldoc -f pack includes
. Null fill or truncate to absolute position specified by value.
which (besides being rather terse) doesn't explicitly say that unpack
"." will do what it does.
Ben
