PHP pack() Function

PHP Miscellaneous Functions

Definition and Usage

The pack() function packs data into a binary string.

Syntax

pack(format,args+)
Parameter Description
format Required. Specifies the format used when wrapping data.
args+ Optional. Specifies one or more parameters to be wrapped.

format Possible values of parameters:

  • 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)
  • f - float (machine dependent size and representation)
  • d - double (machine dependent size and representation)
  • x - NUL byte
  • X - Back up one byte
  • @ - NUL-fill to absolute position

Instance

Example 1

<?php
echo pack("C3",80,72,80);
?>

Output:

PHP

Example 2

<?php
echo pack("C*",80,72,80);
?>

Output:

PHP

PHP Miscellaneous Functions