python - 如何使用 cpython 将结构数组传递给 DLL 函数？

Question

#include <stdio.h>

struct struct_data {
    int price;
    char list[255];
    int count;
};

__declspec(dllexport) void __stdcall testcall(struct struct_data *array_data) {

    int i = 0;
    while(array_data[i].price != 0) {           // array_data is guaranteed to have a zero somewhere inside memory allocated for the array
        printf("%d\n", array_data[i].price);
        i++;
    }

}

我尝试使用 cpython 从 Python 调用它，如下所示:

# C Backend imports
import os
import sys
import ctypes

# load DLL
dll = ctypes.WinDLL('C:\\Users\\user\Documents\\Pelles C Projects\\MarketlibDLL\\MarketlibDLL.dll')

class struct_data(ctypes.Structure):
    _fields_ = [
        ('price', ctypes.c_int),
        ('list', ctypes.c_char * 255),
        ('count', ctypes.c_int),
    ]

d = struct_data() * 100    # I try to do:   struct struct_data d[100]; 
d[0].price = 100
d[0].list = "ABC"
d[0].count = 3
d[1].price = 0

dll.testcall.argtypes = [ctypes.POINTER(struct_data)]
dll.testcall(d)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-2-36161e840b5f> in <module>
----> 1 d = struct_data() * 100
      2 d[0].price = 100
      3 d[0].list = "ABC"
      4 d[0].count = 3
      5 d[1].price = 0

TypeError: unsupported operand type(s) for *: 'struct_data' and 'int'

Answer 1

[Python 3.Docs]: ctypes - A foreign function library for Python具有所有必需的信息(Arrays 部分包含一个完美映射当前场景的示例)。

将您的代码修改为(为了便于阅读，分成两行):

struct_data_array_100 = struct_data * 100  # !!! This is a type (array consisting of 100 struct_data elements) !!!
d = struct_data_array_100()  # Instantiate the array type
#d[0].price ...
# ...