C# function not accepting CLI array in C++

Question

I'm currently writing a program in CLI/C++ using an imported C# package. I need to use one of the functions in one of the C# objects which takes in an array. Unfortunately it isn't allowing me to use a CLI array, defined like so:

array<float>^ knots = gcnew array<float>(nurbs->GetNumKnots());

(and then populated in a loop).

The object and the function are:

TRH::NURBSCurveKit^ nurbsKit = gcnew TRH::NURBSCurveKit();
nurbsKit->SetKnots(nurbs->GetNumKnots(), knots);

This returns an error basically saying that the cli::array type isn't compatible. Does anyone know of a way where I can cast the array, or possibly define it differently?

I'm quite new to CLI so I'm a little vague on the way it handles things at times.

Thanks

(I do something similar later on using an array of TRH::Points, but they're not defined as references or pointers, so I'm not sure if they'd work with any solutions or not).

NURBSCurveKit is a C++ library. Why you are using a C# wrapper (??) for it is very unclear. It certainly doesn't look like a very good wrapper if it won't take an array<float>^. You can't get help unless you avoid us having to guess at this wrapper and what its SetKnots() method looks like. — Hans Passant
– Hans Passant, Commented Dec 5, 2013 at 13:20

David Yaw · Accepted Answer · 2013-12-05 13:24:13Z

1

I'm not sure if it's the same NURBSCurveKit, but according to an online API reference I found, the SetKnots method takes one parameter, not two. Since a managed array knows how long it is, you generally don't have to pass in a length with an array.

If this matches your API, just switch to pass a single parameter to SetKnots. (The reference I found uses a different namespace, so it may not be what you're using.)

array<float>^ knots = gcnew array<float>(nurbs->GetNumKnots());

TRH::NURBSCurveKit^ nurbsKit = gcnew TRH::NURBSCurveKit();
nurbsKit->SetKnots(knots);

answered Dec 5, 2013 at 13:24

David Yaw

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2 Comments

djcmm476 Over a year ago

Huh, it is the same (at least the function works with one argument). An example I had used two arguments, I guess I just jumped to the conclusion that the array was causing the problem. Which...yeah, that was dumb. Thanks very much.

David Yaw Over a year ago

As Hans Passant noted, NURBSCurveKit is a C++ library. Your example is probably using unmanaged C++, where you do need to pass in the length of arrays.

wener · Accepted Answer · 2013-12-05 13:00:56Z

0

This is my test case, seems everything is fine.

C#

namespace CS
{
    public class Test
    {
        public int GetNum()
        {
            return 5;
        }

        public void ShowArray(int num, float[] arr)
        {
            for (int i = 0; i < num; i++)
            {
                Console.WriteLine("[{0}] = {1}",i,arr[i]);
            }
        }
    }
}

C++/CLI

using namespace System;
using namespace CS;

int main(array<System::String ^> ^args)
{
    Test^ test = gcnew Test();
    array<float>^ arr = gcnew array<float>(test->GetNum());

    for (int i = 0; i < test->GetNum(); i ++)
    {
        arr[i] = (float)i * i;
    }
    test->ShowArray(test->GetNum(), arr);
    Console::ReadKey();
    return 0;
}

Dose you code have something different form mine?

answered Dec 5, 2013 at 13:00

wener

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1 Comment

djcmm476 Over a year ago

Hmm, nothing obvious that I can see. It's still saying the cli::array type isn't valid though. :/

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