Question

I am using Asp.net/C# ,, i have declared an integer array as follows public int[] recno;
As i dont know the exact size of the array ,, however inside a function i get to know its size based on the number of customer_id's in the table.Here is the function

public void GetRecordNo()
        {
            recid = from id in dt.cust_masters
                    select id;
            recno = new int[recid.Count()];

            for (int i = 0; i < recid.Count(); i++)
            {
                recno[i] = Convert.ToInt32(recid.ElementAt(i).customer_id);
            }

        }

When i try to call a function ShowRecord(int index) which accepts the id of the customer in the following manner

ShowRecord(recno[0])

It gives me an error

Object reference not set to an instance of an object.

Can anybody point me where am i going wrong.
Thanks

Answer 1

You can simplify your code:

recid = from id in dt.cust_masters
          select id.customer_id;

//recno = new int[recid.Count()];
recno = recid.ToArray();
// remove for-loop

And to find/prevent your null ref problem:

void  ShowRecord(int index)
{
    if (index < 0 || index >= recno.Length)
       throw new InvalidArgumentException("index");

    var id = recno[index];
    ...
}