C++DLL返回从Python调用的指针

C++ DLL returning a pointer called from Python

本文关键字：指针 调用 Python 返回 C++DLL      更新时间：2023-10-16

我正试图从python访问C++dll（我是python新手）。我克服了许多调用约定问题，最终使它在没有任何编译/链接错误的情况下运行。然而，当我在python中打印从C++dll返回的数组时，它显示了所有随机初始化的值。看起来这些值没有正确返回。

我的C++代码是这样的。

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：

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

任何关于我做错了什么的建议都将不胜感激。

而不是

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"的情况下会做什么，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;
}

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

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