首页 > 代码库 > PHP咋项函数之pack
PHP咋项函数之pack
PHP中不属性其他类别的函数就叫杂项函数,也属性PHP的核心组成部分
pack($format,arg+) //把数据装入一个二进制的字符串中
$format:必选,规定在包装数据时所使用的格式。
arg+: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
如实例:
echo pack("S",80); //如果格式S后面没有数据或者具体的数字或者*,则表示后面只能有一个参数,如果后面有具体的数字,则表示后面的参数为这么多个
//P
echo pack("C3",80,72,80); //表示后面只能有3个参数//PHP
$str = null; for($i=0;$i<20;$i++) { $str .= pack("S",mt_rand(80,128)); } echo $str;//m{QXim^wslts_W[kvrSU
echo pack("C*",80,72,80); //表示后面只能有3个参数//PHP
PHP咋项函数之pack