PHP pack() 函数

定义和用法

pack() 函数把数据装入一个二进制字符串。

语法

pack(format,args+)
参数 描述
format 必需。规定在包装数据时所使用的格式。
args+ 可选。规定被包装的一个或多个参数。

format 参数的可能值：

  • 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

例子

例子 1

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

输出：

PHP

例子 2

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

输出：

PHP