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
)
