PHP unpack function

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unpack

(PHP 3, PHP 4, PHP 5)

Unpacks from a binary string into an array according to the given
format.

unpack() works slightly different from Perl as
the unpacked data is stored in an associative array. To
accomplish this you have to name the different format codes and
separate them by a slash /.

See pack() for an explanation of the format codes.

The packed data.

Returns an associative array containing unpacked elements of binary
string.

Example 1. unpack() example

$array = unpack("c2chars/nint", $binarydata);

The resulting array will contain the entries “chars1″,
“chars2″ and “int”.

Note that PHP internally stores integral values as signed. If you
unpack a large unsigned long and it is of the same size as PHP
internally stored values the result will be a negative number
even though unsigned unpacking was specified.