我试图使用ctypes
。我对操纵包含数组的C结构感兴趣。请考虑以下my_library.c
#include <stdio.h>
typedef struct {
double first_array[10];
double second_array[10];
} ArrayStruct;
void print_array_struct(ArrayStruct array_struct){
for (int i = 0; i < 10; i++){
printf("%f\n",array_struct.first_array[i]);
}
}
并假设我已在共享库中编译它my_so_object.so
从Python我可以做这样的事情
import ctypes
from ctypes import *
myLib = CDLL("c/bin/my_so_object.so")
class ArrayStruct(ctypes.Structure):
_fields_ = [('first_array', ctypes.c_int * 10), ('second_array', ctypes.c_int * 10)]
def __repr__(self):
return 'ciaone'
myLib.print_array_struct.restype = None
myLib.print_array_struct.argtype = ArrayStruct
my_array_type = ctypes.c_int * 10
x1 = my_array_type()
x2 = my_array_type()
a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
x1[0:9] = a[0:9]
a = [11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
x2[0:9] = a[0:9]
print(my_array_type)
>>> <class '__main__.c_int_Array_10'>
print(x1[2])
>>> 3
print(x2[2])
>>> 13
x = ArrayStruct(x1, x2)
print(x.first_array[0:9])
>>> [1, 2, 3, 4, 5, 6, 7, 8, 9]
到目前为止一直很好:我已经创建了正确的类型,一切似乎都运行良好。但那时:
myLib.print_array_struct(x)
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
>>> 0.000000
我显然遗漏了一些东西。识别ArrayStruct
类型(否则调用myLib.print_array_struct(x)
会抛出错误)但未正确初始化。
答案 0 :(得分:1)
代码存在2个问题(正如我在评论中所述):
print_array_struct.argtype
- 这是不正确的ctypes.c_int
( int )基于有关详情,请查看[Python 3]: ctypes - A foreign function library for Python。
我修改了你的 Python 代码,以纠正上述错误(以及其他一些小问题)。
code.py :
#!/usr/bin/env python3
import sys
import ctypes
DLL_NAME = "./my_so_object.so"
DOUBLE_10 = ctypes.c_double * 10
class ArrayStruct(ctypes.Structure):
_fields_ = [
("first_array", DOUBLE_10),
("second_array", DOUBLE_10),
]
def main():
dll_handle = ctypes.CDLL(DLL_NAME)
print_array_struct_func = dll_handle.print_array_struct
print_array_struct_func.argtypes = [ArrayStruct]
print_array_struct_func.restype = None
x1 = DOUBLE_10()
x2 = DOUBLE_10()
x1[:] = range(1, 11)
x2[:] = range(11, 21)
print([item for item in x1])
print([item for item in x2])
arg = ArrayStruct(x1, x2)
print_array_struct_func(arg)
if __name__ == "__main__":
print("Python {:s} on {:s}\n".format(sys.version, sys.platform))
main()
<强>输出强>:
[cfati@cfati-ubtu16x64-0:~/Work/Dev/StackOverflow/q050447199]> python3 code.py Python 3.5.2 (default, Nov 23 2017, 16:37:01) [GCC 5.4.0 20160609] on linux [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0] [11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0] 1.000000 2.000000 3.000000 4.000000 5.000000 6.000000 7.000000 8.000000 9.000000 10.000000