PHP unpack() Function
❮ PHP Misc Reference
Example
Unpack data from a binary string:
<?php
$data = "PHP";
print_r(unpack("C*",$data));
?>
Try it Yourself »
Definition and Usage
The unpack() function unpacks data from a binary string.
Syntax
Parameter Values
| Parameter |
Description |
| format |
Required. Specifies the format to use when unpacking data.
Possible values:
- a - NUL-padded string
- A - SPACE-padded string
- h - Hex string, low nibble first
- H - Hex 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 (machine dependent size and byte order)
- I - unsigned integer (machine dependent 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)
- q - signed long long (always 64 bit, machine byte order)
- Q - unsigned long long (always 64 bit, machine byte order)
- J - unsigned long long (always 64 bit, big endian byte order)
- P - unsigned long long (always 64 bit, little endian byte order)
- f - float (machine dependent size and representation)
- g - float (machine dependent size, little endian byte order)
- G - float (machine dependent size, big endian byte order)
- d - double (machine dependent size and representation)
- e - double (machine dependent size, little endian byte order)
- E - double (machine dependent size, big endian byte order)
- x - NUL byte
- X - Back up one byte
- Z - NUL-padded string
- @ - NUL-fill to absolute
|
| data |
Required. Specifies the binary data to be unpacked |
| offset |
Optional. Specifies where to start unpacking from. Default is 0. |
Technical Details
| Return Value: |
Returns an array on success, or FALSE on failure. |
| PHP Version: |
4+ |
| Changelog: |
PHP 7.2 - float and double now supports both big and small endian.
PHP
7.1 - Added the optional offset parameter.
PHP 5.5.0 - The following changes were made for Perl compatibility:
The "a" code now retains trailing NULL bytes.
The "A" code now strips all trailing ASCII whitespace.
The "Z" code was added for NULL-padded strings, and removes trailing NULL bytes. |
More Examples
Example
Unpack data:
<?php
$data = "PHP";
print_r(unpack("C*myint",$data));
?>
Try it Yourself »
Example
Unpack data:
<?php
$bin = pack("c2n2",0x1234,0x5678,65,66);
print_r(unpack("c2chars/n2int",$bin));
?>
Try it Yourself »
❮ PHP Misc Reference
