# 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 ) ```