P调用返回指针的C函数 [英] PInvoke C function that return pointer

问题描述

我有一个这样的C函数:

Hi,
I have a C function like this:

double* foo() // function return array of 10 double
{
double* matrix  = (double *)malloc(10 * sizeof(double));
return matrix;
}

如何在包装器类中编写?我应该这样做吗?

how can I write in the wrapper class? Should I do that?

[DllImport("...")]
[return: MarshalAs(UnmanagedType..LPArray)]
public static extern double foo();

请告诉我方法.

Please tell me the way.

推荐答案

[DllImport("...")]
public static extern IntPtr foo();

应该管用.然后，如果您知道数组的大小:

Should work. Then if you know the size of the array:

IntPtr result = foo();
double[] arr = new double[10];
Marshal.Copy(result, arr, 0, 10);

如果数组大小不是静态的，则应返回数组大小，如下所示:

If the array size isn''t static, then you should return the size of the array like this:

double* foo(int* size) // function return array of 10 double
{
double* matrix  = (double *)malloc(10 * sizeof(double));
*size = 10;
return matrix;
}

并使用:

And use:

[DllImport("...")]
public static extern IntPtr foo(out int size);

...

int size;
IntPtr result = foo(out size);
double[] arr = new double[size];
Marshal.Copy(result, arr, 0, size);

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