PHP unpack()Functions

Examples

Unpack data from a binary string:

<?php
$data = "PHP";
print_r(unpack("C*",$data));
?>

The unpack() function unpacks data from a binary string.

unpack(format,data)

Parameters	Description
format	Required. Specifies the format to use when unpacking data. Possible values: a - NUL-padded string A - SPACE-padded string h - Hexadecimal string, low nibble first H - Hexadecimal string, high nibble first c - signed char C - unsigned char s - signed short (always 16-bit, machine byte order) S - unsigned short (always 16-bit, machine byte order) n - unsigned short (always 16-bit, big endian byte order) v - unsigned short (always 16-bit, little endian byte order) i - signed integer (depends on machine size and byte order) I - unsigned integer (depends on machine size and byte order) l - signed long (always 32-bit, machine byte order) L - unsigned long (always 32-bit, machine byte order) N - unsigned long (always 32-bit, big endian byte order) V - unsigned long (always 32-bit, little endian byte order) f - float (depends on machine size and representation) d - double (depends on machine size and representation) x - NUL byte X - Back up one byte Z - NUL-padded string @ - NUL-fill to absolute position
data	Required. Specifies the binary data to be unpacked.

Parameters

Description

format

Required. Specifies the format to use when unpacking data.

Possible values:

data

Required. Specifies the binary data to be unpacked.

Return value:	Returns an array on success, or FALSE on failure.
PHP Version:	4+
Changelog:	As of PHP 5.5.0, the following changes were made for Perl compatibility: The "a" code retains trailing NULL bytes. The "A" code removes all trailing ASCII whitespace. Added the "Z" code for NUL-padded strings, which removes trailing NULL bytes.

Unpack the data:

<?php
$data = "PHP";
print_r(unpack("C*myint",$data));
?>

Unpack the data:

<?php
$bin = pack("c2n2",0x1234,0x5678,65,66);
print_r(unpack("c2chars/n2int",$bin));
?>