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)

format 参数的可能值：

1. a - NUL-padded string
2. A - SPACE-padded string
3. h - Hex string, low nibble first
4. H - Hex string, high nibble first
5. c - signed char
6. C - unsigned char
7. s - signed short (always 16 bit, machine byte order)
8. S - unsigned short (always 16 bit, machine byte order)
9. n - unsigned short (always 16 bit, big endian byte order)
10. v - unsigned short (always 16 bit, little endian byte order)
11. i - signed integer (machine dependent size and byte order)
12. I - unsigned integer (machine dependent size and byte order)
13. l - signed long (always 32 bit, machine byte order)
14. L - unsigned long (always 32 bit, machine byte order)
15. N - unsigned long (always 32 bit, big endian byte order)
16. V - unsigned long (always 32 bit, little endian byte order)
17. f - float (machine dependent size and representation)
18. d - double (machine dependent size and representation)
19. x - NUL byte
20. X - Back up one byte
21. @ - NUL-fill to absolute position

实例

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
)