python中的等价C联合？

Question

假设我在C中有以下代码

union u_type
{
    uint32_t data;
    uint8_t  chunk[4];
} 32bitsdata;

32bitsdata.chunk[0] = some number;
32bitsdata.chunk[1] = some number;
32bitsdata.chunk[2] = some number;
32bitsdata.chunk[3] = some number;

printf("Data in 32 bits: %d\n", 32bitsdata.data);

我怎么能在python中做类似的事情？

我正在尝试读取二进制文件(逐字节) - 已经使它工作,并将每3个字节组合成一个int.听说结构会起作用,但我不确定如何.

最好,

亨利

Answer 1

那个ctypes怎么样？

from ctypes import (
        Union, Array, 
        c_uint8, c_uint32, 
        cdll, CDLL
) 

class uint8_array(Array):
    _type_ = c_uint8
    _length_ = 4

class u_type(Union):
    _fields_ = ("data", c_uint32), ("chunk", uint8_array)

# load printf function from Dynamic Linked Libary libc.so.6 (I'm use linux)
libc = CDLL(cdll.LoadLibrary('libc.so.6')._name)
printf = libc.printf

if __name__ == "__main__":
    # initialize union
    _32bitsdata = u_type()
    # set values to chunk
    _32bitsdata.chunk[:] = (1, 2, 3, 4)
    # and print it
    printf(b"Data in 32 bits: %d\n", _32bitsdata.data)