# unpack

(PHP 4, PHP 5)

unpack — Unpack data from binary string

### Description

array unpack ( string `$format` , string `$data` )

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 /.

### Parameters

`format`

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

`data`

  The packed data.

### Return Values

Returns an associative array containing unpacked elements of binary string.

### Examples

Example#1 unpack() example

`<?php
$array = unpack("c2chars/nint", $binarydata);
?>`

The resulting array will contain the entries "chars1", "chars2" and "int".

### Notes

Caution

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.

### See Also

- pack()