unpack

unpack

Unpack data from binary string

 **unpack** string $format string $string int $offset

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

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 /. If a repeater argument is present, then each of the array keys will have a sequence number behind the given name.

Changes were made to bring this function into line with Perl:

format See for an explanation of the format codes. pack

stringThe packed data.

offsetThe offset to begin unpacking from.

Returns an associative array containing unpacked elements of binary string, return.falseforfailure.

Voorbeeld: example

<?php
$binarydata = "\x04\x00\xa0\x00";
$array = unpack("cchars/nint", $binarydata);
print_r($array);
?>

Array
(
    [chars] => 4
    [int] => 160
)

Voorbeeld: example with a repeater

<?php
$binarydata = "\x04\x00\xa0\x00";
$array = unpack("c2chars/nint", $binarydata);
print_r($array);
?>

Array
(
    [chars1] => 4
    [chars2] => 0
    [int] => 40960
)

Let op: > 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.

Let op: > If you do not name an element, numeric indices starting from are used. Be aware that if you have more than one unnamed element, some data is overwritten because the numbering restarts from for each element. 1``1

Voorbeeld: example with unnamed keys

<?php
$binarydata = "\x32\x42\x00\xa0";
$array = unpack("c2/n", $binarydata);
var_dump($array);
?>

array(2) {
  [1]=>
  int(160)
  [2]=>
  int(66)
}

  Note that the
  first value from the  specifier is 
  overwritten by the first value from the 
  specifier.
 `c``n`

pack