Question Array and struct

[johnix]

hi,
i've this code

public class a
{
    sa sa1 = new sa(0);
        
    public void test ()
    {
        uint i, j; 

        for (i = 0; i <= 1; i += 1) {
            for (j = 0; j <= 13; j += 1) {
                sa1.va[i].vb[j] = false;
            }
        }
    }
        
    public struct sa
    {
        public sb[] va;
    
        public sa(uint i): this()
        {
            va = new sb[2];
        }
    }

    public struct sb
    {
        public bool[] vb;

        public sb(uint i): this()
        {
            vb = new bool[14];
        }
    }
}

When i try to run void test i receive this error: ...Object reference not set to an instance of an object"
where am I doing wrong?

 

[jmcilhinney]

In your `sa` constructor, you create the array by specifying a length but you never create `sb` objects to assign to the elements. That means that the `sb` constructor that you wrote never gets invoked and therefore the `vb` array in each `sb` object is never set, therefore it's null for each element. Most likely you shouldn't be using structures at all but rather classes.

To prove it to yourself, place a breakpoint on each structure constructor using the F9 key. When you run the code, you'll see one of them get hit but the other one not.