[Jim Hill wrote]
[...]
> Flags=1414
>
> ... which is linked to a set of gui checkboxes - some, but not
> all, of which are mutually exclusive. Checking each option in
> turn and monitoring the .cfg file results in this table ...
>
> 0 no flags set
> 1 subscriber is suspended
> 2 receives list messages
> 4 posts lists messages
> 8 subscriber is list administrator
> 16 subscriber is moderated
> 32 subscriber is barred
> 64 receives multipart/mixed digests
> 128 receives binaries
> 256 posts binaries
> 512 receives multipart/digest digests
> 1024 receives text/plain digests
> 2048 public membership
> 4096 concealed subscription address
> 8192 force text/plain posts
>
> Is there a module or a perl algorithm for determining which of
> the 14 checkboxes are enabled from a "Flags=" value?
[Mark Messenger wrote]
[...]
> $bitstring=unpack(b16,$flags);
> print "Bitstring is $bitstring\n"; # 1000110000101100 for 1414
Actually, given $flags == 1414, this is unpacking the _string_ "14"
(0x31 0x34). unpack() expects its 2nd arg to be a string, so Perl
passes the _string_ value of $flags, "1414", to unpack() (only the
first 2 chars of "1414" are used because of the 'b16' template).
To pass unpack() the appropriate byte stream, use pack() first. Such as:
$bitstring = unpack('b16', pack('S', $flags));
# $bitstring == '0110000110100000' LSB -> MSB
As I prefer the MSB (Most Significant Bit) on the left, I would probably
be more likely to use:
$bitstring = sprintf('%0.16b', 1414);
# $bitstring == '0000010110000110' MSB -> LSB
If you would prefer the decimal values of the bits set, consider:
my @bits = ();
for (8192, 4096, 2048, 1024, 512, 256, 128, 64, 32, 16, 8, 4, 2, 1) {
push(@bits, $_) if $flags & $_;
}
# Given $flags == 1414, @bits will contain (1024, 256, 128, 4, 2)
If you want the text corresponding to each checkbox, see $Bill's post.
Hmm...Let me slightly tweak his suggestion and sort the keys in numeric
order and include the bit value in the output - might make it easier to
compare with the checkbox list.
use strict;
my $flags = 1414; # Just to be consistent with the other examples
my %hash = (1 => 'Subscriber is Suspended', 2 => 'Receives List
Messages', ...);
foreach (sort {$a <=> $b} keys %hash) {
printf "%4d %s\n", $_, $hash{$_} if $flags & $_;
}
This prints:
2 receives list messages
4 posts lists messages
128 receives binaries
256 posts binaries
1024 receives text/plain digests
HTH,
Jonathan D Johnston
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