python - C++ DLL 返回一个从 Python 调用的指针

Question

我正在尝试从 python 访问 C++ dll(我是 Python 的新手)。我克服了许多调用约定问题，并最终让它在没有任何编译/链接错误的情况下运行。但是，当我在 python 中打印从 C++ dll 返回的数组时，它会显示所有随机初始化值。看起来值没有正确返回。

我的 C++ 代码如下所示。

double DLL_EXPORT __cdecl *function1(int arg1, int arg2, double arg3[],int arg4,double arg5,double arg6,double arg7, double arg8)
{     
        double *Areas = new double[7];

        ....Calculations

        return Areas;
}

我的 python 代码如下所示:

import ctypes

CalcDll = ctypes.CDLL("CalcRoutines.dll")

arg3_py=(ctypes.c_double*15)(1.926,1.0383,0.00008,0.00102435,0.0101,0.0,0.002,0.0254,102,1,0.001046153,0.001046153,0.001046153,0.001046153,20)
dummy = ctypes.c_double(0.0)

CalcDll.function1.restype = ctypes.c_double*7
Areas = CalcDll.function1(ctypes.c_int(1),ctypes.c_int(6),arg3_py,ctypes.c_int(0),dummy,dummy,dummy,dummy)

for num in HxAreas:
    print("\t", num)

打印语句的输出如下:

     2.4768722583947873e-306
     3.252195577561737e+202
     2.559357001198207e-306
     5e-324
     2.560791130833573e-306
     3e-323
     2.5621383435212475e-306

非常感谢任何关于我做错的建议。

Answer 1

代替

CalcDll.function1.restype = ctypes.c_double * 7

应该有

CalcDll.function1.restype = ctypes.POINTER(ctypes.c_double)

然后

Areas = CalcDll.function1(ctypes.c_int(1), ctypes.c_int(6), arg3_py,
                          ctypes.c_int(0), dummy, dummy, dummy, dummy)

for i in range(7):
    print("\t", Areas[i])

我不确定 ctypes 在 'ctypes.c_double * 7' 的情况下做了什么，如果它试图从堆栈中提取七个 double 或什么。

测试

double * function1(int arg1, int arg2, double arg3[],
                   int arg4, double arg5, double arg6,
                   double arg7, double arg8)
{
    double * areas = malloc(sizeof(double) * 7);
    int i;

    for(i=0; i<7; i++) {
        areas[i] = i;
    }

    return areas;
}

数组中的值使用 restype = ctypes.POINTER(ctypes.c_double) 正确打印