program error when enter data in array and display null

Question

i have done some correction by referring in here, but still haven quite satisfy of my program and it still not complete.
Problem 1 = my displayReg() comes out \"nullnullnull

Answer 1

int i = 0;
Register[] a = new Register[i];   

You are effectively attempting to create an array of 0 size. But when you try to access a[i] when i = 0, it attempts to access the element at 1'st position in the array (array have 0 as the first position).

Also you have put it in a while loop which means you create a new array of 0 size on every loop cycle.

try putting i = 10 (or whatever your program logic says) and put the array creation out of the loop

Answer 2

Register[] a = new Register[i]; - creates an array with 0 items.

a[i].Reg(); - access to the position 0 of an array that got no items at all.

Here is a tutorial