Populate 2D arrays using a loop

Question

I'm attempting to parse a pipe delimited line of text from a file - HL7 message segment - to make the segment a property of an HL7 message object.

I think I"m fundamentally not understanding the concept of n-dimensional arrays...

The segment looks like this

MSH|^~\&||X530^X530^FID|ERIC^NSCC^RSSI|NSCCH|....

I want to create an array thusly;

First item in the array = {"0","MSH"}

Next item in the array = {"1,", "^~\&"}

Next item in the array = {"2,", null}

Next item in the array = {"3,", "X530^X530^FID"}

I get error message:

    private string [,] ParseSegment(string ms)
    {
        int i = 0;
        string[] segmentFields = ms.Split('|');//fields for this segment
        int arrayLength = segmentFields.Length;
        string[,] fieldAndIndex = new string[arrayLength,1];

        foreach (string field in segmentFields)
        {
            fieldAndIndex [i,i] = {{ i,field} };//I'm not sure what to do here!!!!
        }

        return fieldAndIndex;
    }

Answer 1

Each sub array of your 2D array has 2 items (right?), so you should have a 2 instead of a 1 as the length:

string[,] fieldAndIndex = new string[arrayLength, 2];

Since you want a counter variable I in the loop, you should not use a foreach loop:

for (int i = 0 ; i < arrayLength ; i++) {
    // here you want the first item of the subarray to be i, and the second item to be the corresponding segment
    fieldAndIndex[i, 0] = i.ToString();
    fieldAndIndex[i, 1] = segmentFields[i];
}

Also, I don't think a 2D array is suitable here. Storing the index of each element (which is what you seem to be trying to do) is unnecessary, because fieldAndIndex[x, 0] will always be the same as x!

You might want to use a simple 1D array instead. There are other data structures that might be useful:

• Dictionary<int, string>
• (int, string)[]
• string[][]

Answer 2

To understand the basic array in your case you can consider the array to be a 2D Matrix. Similarly you can consider a 3D array a cube. What you are trying to do is add two item in one place

fieldAndIndex [i,i] = {{ i,field} };

So during the first iteration the notation [i,i] evaluates to [0,0] which means the first element in the first row. The proper way to insert these both can be done as shown by the given answer

fieldAndIndex [i,i] = i.ToString();
fieldAndIndex [i,++i] = field.ToString();

I hope this resolves your issue it is better to go through some research on multi dimensional arrays. This and This are some good links to get started on these arrays.