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

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unpack(format,data)

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

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

输出：

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

例子 2

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

输出：

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

例子 3

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

输出：

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