Question

我正在尝试使用Python与＆＃34; ReturnBuffer＆＃34;我创建的DLL中的函数，并遇到了缓冲值似乎没有被函数修改的问题。＆＃34; ReturnBuffer＆＃34;函数有两个参数，缓冲区的长度和指向缓冲区的指针，我想知道我是否正确传递指针。我写了c函数，如下所示：

__declspec(dllexport) int ReturnBuffer (int num_numbers, unsigned __int32 *buffer);

int ReturnBuffer (int num_numbers, unsigned __int32 *buffer)
{
    int i;
    for (i = 0; i < num_numbers; i++) {
    buffer[i] = buffer[i] + i ;
    }
    return 1;
}

我使用下面的python代码加载DLL：

_file = 'MyMathDLL.dll'
_path = os.path.join(*(os.path.split(__file__)[:-1] + (_file,)))
_math = ctypes.cdll.LoadLibrary(_path)

然后我创建一个1的数组并将数组的长度和数组的指针传递给函数＆＃34; ReturnBuffer＆＃34;，我的期望是该函数将获取指针并修改缓冲区中的值。

_math.ReturnBuffer.restype = ctypes.c_int
_math.ReturnBuffer.argtypes = [ctypes.c_int, ctypes.POINTER(ctypes.c_uint32)]

nelem = 10
variable = ctypes.c_double(10.0)
Buffer_Type = ctypes.c_uint32 * nelem
Buffer = (1,1,1,1,1,1,1,1,1,1)

print(_math.ReturnBuffer(ctypes.c_int(nelem),Buffer_Type(*Buffer)))
print(Buffer)

Screen Output:
1
(1, 1, 1, 1, 1, 1, 1, 1, 1, 1)

Process finished with exit code 0

Answer 1

数组初始化在文档中描述：https://docs.python.org/2/library/ctypes.html

试试这个：

Buffer = (ctypes.c_uint32 * nelem)()
for i in range(0, nelem):
    Buffer[i] = 1
print(_math.ReturnBuffer(nelem, Buffer))
print(Buffer)

或者这个：

Buffer = (ctypes.c_uint32 * nelem)(1, 1, 1, 1, 1, 1, 1, 1, 1, 1)
print(_math.ReturnBuffer(nelem, Buffer))
print(Buffer)

通过Python中的Ctypes传递指向DLL的指针

1 个答案: