Misc. Funções
PHP Manual

unpack

(PHP 4, PHP 5, PHP 7)

unpackUnpack data from binary string

Descrição

array unpack ( string $format , string $data )

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.

Parâmetros

format

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

data

The packed data.

Valor Retornado

Returns an associative array containing unpacked elements of binary string.

Changelog

Versão Descrição
5.5.0

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

The "a" code now retains trailing NULL bytes.

The "A" code now strips all trailing ASCII whitespace (spaces, tabs, newlines, carriage returns, and NULL bytes).

The "Z" code was added for NULL-padded strings, and removes trailing NULL bytes.

Exemplos

Exemplo #1 unpack() example

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

O exemplo acima irá imprimir:

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

Exemplo #2 unpack() example with a repeater

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

O exemplo acima irá imprimir:

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

Notas

Cuidado

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.

Cuidado

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

Exemplo #3 unpack() example with unnamed keys

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

O exemplo acima irá imprimir:

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

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

Veja Também


Misc. Funções
PHP Manual