定義和用法

unpack() 函數(shù)從二進制字符串對數(shù)據(jù)進行解包。

語法

unpack(format,data)

參數(shù)	描述
format	必需。規(guī)定在解包數(shù)據(jù)時所使用的格式。
data	可選。規(guī)定被解包的二進制數(shù)據(jù)。

format 參數(shù)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));
?>

輸出：

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

例子 2

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

輸出：

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

例子 3

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

輸出：

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