Pinvoking a native function with array arguments

Question

I am completely confused with how to go about calling functions in native dll with array arguments.

Example:

The function is defined in the C# project as:

Answer 1

Your C++ code is broken. The caller allocates the array, and the callee populates it. Like this:

extern "C" _declspec(dllexport) void modifyArray(int* x, int len)
{   
    for (int i=0; i

As far as your p/invoke call goes, SetLastError should not be true. The function is not calling SetLastError. It should be:

[DllImport("Project2.dll", CallingConvention = CallingConvention.Cdecl)]
static extern void modifyArray(int[] x, int len);