How do I convert 2d CLR array to C++ pointer double*

Question

0.00/5 (No votes)

See more:

Hello
I am trying to convert a 2d CLR array to a single pointer array in C++. here is my code:

C++

array<array<double>^>^ myarray =
	{
		{1,2,3,4},
		{5,6,7,8}
	};
	pin_ptr<double> p = &myarray[0][0];
	double* R = p;

	for (size_t i = 0; i < 2; i++)
	{
		for (size_t j = 0; j < 4; j++)
		{
			Console::WriteLine(R[i, j]);
		}
	}

The problem is that R hold only the first row of my 2d array....
if I do the same thing in normal c++ The

variable hold my entire array

How can I solve this problem ?

What I have tried:

I really do not know how to solve this issue...

Posted 2-Feb-21 1:09am

MohammadrezaMC2

Updated 2-Feb-21 21:14pm

Add a Solution

Comments

Shao Voon Wong 2-Feb-21 7:13am

Why do you want to pin it?

MohammadrezaMC2 2-Feb-21 7:27am

There is a mathematical library in c++ called Armadillo, in order for me to use this I must convert my 2d array to a single pointer double* and then use Armadillo...

11917640 Member 2-Feb-21 9:36am

You need to pin pointer for every line.

MohammadrezaMC2 3-Feb-21 0:36am

How should I do it ?

11917640 Member 2-Feb-21 9:49am

myarray in your code is jagged array. See the difference here: https://docs.microsoft.com/en-us/cpp/dotnet/how-to-use-arrays-in-cpp-cli?view=msvc-160 multi-dimension managed array vs jagged array.

1 solution

Add a Solution

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Shao Voon Wong · Answer 1 · 2021-02-02T21:14:00

You do not need to pin. Just assign one element at a time to the native mat variable, R.

C++

array<array<double>^>^ myarray =
    {
        {1,2,3,4},
        {5,6,7,8}
    };
    
mat R(2,4);

for (size_t i = 0; i < 2; i++)
{
    for (size_t j = 0; j < 4; j++)
    {
        R(i, j) = myarray[i][j];
    }
}

How do I convert 2d CLR array to C++ pointer double*

1 solution

Solution 1

Add your solution here

Preview 0

How do I convert 2d CLR array to C++ pointer double*

1 solution

Solution 1

Add your solution here

Preview 0

Existing Members

...or Join us