c++ jagged array slice in c#

Question

In c++ is possible to get a slice of multidimensional array, like

  double parallelopipedPts[8][3];
  parallelopipedPts[0];
  parallelopipedPts[1];
  ...
  parallelopipedPts[7];

In c# I am trying to emulate this and tried

  double[][] parallelopipedPts = new double[8][];
  parallelopipedPts[0];
  parallelopipedPts[1];
  ...
  parallelopipedPts[7];

However I am getting memory access issues

How to solve this?

Can you expand a bit? What element are you hoping to return? Or are you trying to return the address of the element? — Simon Whitehead, Dec 10 '13 at 01:10
I would like to get a slice (one dimension) of jagged array, How to do that in c#? — edgarmtze, Dec 10 '13 at 01:13
You can't. See here: http://stackoverflow.com/a/4802062/1517578 — Simon Whitehead, Dec 10 '13 at 01:15
On that question OP states he uses a Rectangular array, however if one uses a jagged array, would it be faster as stated in an answer from that question? — edgarmtze, Dec 10 '13 at 01:17

score 1 · Accepted Answer · answered Dec 10 '13 at 01:18

1

In your C# code, you've created an array of 8 'double arrays'.

The double arrays in that array-of-8 have not yet been assigned, so they are null.

You can populate it with arrays-of-3-doubles (for example) like this:

for (int i = 0; i < parallelopipedPts.Length; i++)
{
    parallelopipedPts[i] = new double[3];
}

Then you can safely use your sub-arrays.

answered Dec 10 '13 at 01:18

Baldrick

Nope, double[][] parallelopipedPts = new double[8][3]; would not compile. – Baldrick Dec 10 '13 at 01:24
Is a for loop the only way out? – edgarmtze Dec 10 '13 at 02:57
I guess to be fair I've never bothered trying to make an array like this in C#, since I'd rather build a specialized class with a bit more information attached. – Magus Dec 10 '13 at 15:42

1 Answers1