How do I fix this "Object reference not set to an instance of an object" error?

Question

I am getting a System.NullReferenceException error when I run this program.
It is saying that

the object reference is not set to an instance of an object

But I pretty sure that that's exactly what I am doing in line 11. Any ideas on how to fix this are very much appreciated.

Answer 1

At line 11 you init an array with length 2 but is is still empty to fill it add

csa[0] = new CurryStudent();
csa[1] = new CurryStudent();

Answer 2

You create a list of CarryStudent[] csa. Then you ask for the first element in that list. But your first element in that list is nothing yet, you did not populate your list with elements of type CarryStudent. Thus the exception

Answer 3

csa is an array of instances of a user-defined class called CurryStudent. On line number 11 you instantiated the array of CurryStudent class. Here you forgot to fill an array with its elements that are nothing but an instance of CurryStudent class.

You need to instanciate each element of csa array with an instance of class CurryStudent. Like,

for(int i = 0; i < csa.Length; i++)
    csa[i] = new CurryStudent();