Re: pack it in

On Jan 24, 2008 7:13 PM, Jochem Maas <jochem@iamjochem.com> wrote: > ok. that's where my brain goes to mush - all strings in php (for now) > are binary ... what's the difference between the binary strings > in php and such found in these 'binary files' that they need to be > packed/unpacked? > > sorry if I'm sounding retarded ... I probably am :-/ > pack() allows you to format binary data. it can be formatted for specific architectures as well. formating of php stings does not take place on a binary level, rather it occurs on a byte level, or multibyte using the multibyte string functions http://www.php.net/manual/en/ref.mbstring.php here is a nice example i found from phpdig.net, that is designed to determine whether a system is little, big, or middle endian. (there is a small error on the script at the actual website; ive modified it for the post here and sent a notice to the site regarding it). id like to see how this could be done w/ regular php strings :) <?php # A hex number that may represent 'abyz' $abyz = 0x6162797A; # Convert $abyz to a binary string containing 32 bits # Do the conversion the way that the system architecture wants to switch (pack ('L', $abyz)) { # Compare the value to the same value converted in a Little-Endian fashion case pack ('V', $abyz): echo 'Your system is Little-Endian.'; break; # Compare the value to the same value converted in a Big-Endian fashion case pack ('N', $abyz): echo 'Your system is Big-Endian.'; break; default: $endian = "Your system 'endian' is unknown." . "It may be some perverse Middle-Endian architecture."; } ?> -nathan