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unpack

李清波 2015-10-01 其他



PHP unpack() 函数

定义和用法

unpack() 函数从二进制字符串对数据进行解包。


语法

unpack(format,data)


参数描述
format必需。规定在解包数据时所使用的格式。
data可选。规定被解包的二进制数据。


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
$data = "PHP";
print_r(unpack("C*",$data));
?>

输出:

Array
(
[1] => 80
[2] => 72
[3] => 80
)


例子 2

<?php
$data = "PHP";
print_r(unpack("C*myint",$data));
?>

输出:

Array
(
[myint1] => 80
[myint2] => 72
[myint3] => 80
)


例子 3

<?php
$bin = pack("c2n2",0x1234,0x5678,65,66);
print_r(unpack("c2chars/n2int",$bin));
?>

输出:

Array
(
[chars1] => 52
[chars2] => 120
[int1] => 65
[int2] => 66
)


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