pack php 详解_函数pack的使用详解

[导读]pack函数把数据装入一个二进制字符串。

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<?phpecho  pack("c3",80,72,80);?>

输出：php

例子 2<?phpecho  pack("c*",80,72,80);?>

输出：php