pack

pack

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

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

输出:

例子 2

输出:

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