Passing an array argument from C# to a C++/CLI method

Question

I know only very little about C++/CLI, but I have a simple problem that needs a solution. I have a C++/CLI class method that takes a byte-array as a parameter. The array is of a pre-determined length, and can be allocated in C# beforehand. The array is supposed to be filled with data by the C++/CLI method.

How do I declare the method and then call it from C#?

I tried something like having the following in my C++/CLI class:

public ref class C
{
public:
    void FillBytes(array<BYTE^>^ bytes);
};

And then, in C#:

o = new C();
var bytes = new byte[3];
o.FillBytes(bytes);

But that didn't work at all :).

I made a typo at first, when I wrote array<BOOL^>^ instead of array<BYTE^>^ — jco
– jco, Commented Apr 12, 2010 at 17:43

Omar Bermudez · Accepted Answer · 2014-02-13 19:03:06Z

10

I know this question was asked a long time ago but hopefully it will help someone else who is checking this post. From C++/CLI you need to send this:

void FillBytes(array<unsigned char>^% bytes);

The "hat" means its a CLR type and the % means you will pass it by reference so that the C++/CLI fills the array.

Then you can call it from C# like this:

o = new C();
var bytes = new byte[3];
o.FillBytes(ref bytes);

Hope it helps someone!

answered Feb 13, 2014 at 19:03

Omar Bermudez

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1 Comment

m-abdi Over a year ago

How would you change this for a dynamic array?

dtb · Accepted Answer · 2010-04-12 17:45:54Z

9

Have you tried using byte instead of a BOOL reference?

void FillBytes(array<System::Byte>^ bytes);
                                ↑
                           //   no ^ here

edited Apr 12, 2010 at 17:45

answered Apr 12, 2010 at 17:37

dtb

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1 Comment

jco Over a year ago

Oops, I just typed in some simplified version of my actual code and made a typo. But the problem still remains. I get "Argument '1': cannot convert from 'byte[]' to 'System.ValueType[]'", when trying to compile the above code.

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