Passing array between forms and managing in arrays

Question

I want to transfer an array from Form1 to Form2, then on Form2 add some values to the array. On Form1 button click I put this code:

        int[] arrayOfInt          


        

Answer 1

Rather use ArrayList or even better IList<T>. Arrays cannot be resized in C#

Answer 2

Use List<Int> and use oList.Add(item) method to add elements as array is Fixed in Lenght (you already giving it size at a time of initialization) But if you want to use array at any cost then make a logic to create a new array upto the size of Old+ new added element and return that.

UPDATED I believe you are facing problem because you have taken List of String instead or Int.

            List<int> oIntList = new List<int>();
            oIntList.Add(1);
            oIntList.Add(3);
            oIntList.Add(4);
            oIntList.Add(5);

            int[] oIntArr = oIntList.ToArray();

Answer 3

You will have to use ref argument on frm2.TakeThis() method:

Here is an MSDN article on it : Passing Arrays Using ref and out (C# Programming Guide).

void TakeThis(ref Int32[] array)
{
    // Change array
}

and use like:

frm2.TakeThis(ref arrayOfInt);

Arrays need to passed by reference if you want to persist changes to them.

If you must not use an Array use a Collection like System.Collections.Generic.List<T>.

Answer 4

Don't use arrays if you want a data structure that you need to add items to.

Use a generic collection like List<T>.

In your case, a list of integers would be a List<int>.

IList<int> listOfInt = new List<int>();
listOfInt.Add(19);
listOfInt.Add(12);
Form2 frm2 = new Form2();
frm2.TakeThis(listOfInt);
frm2.Show();

When on Form2, your TakeThis function would look like this:

public voidTakeThis(IList<int> listOfInt)
{
  listOfInt.Add(34);
}

This will also work when passing the list to another form, as List is a reference type whereas arrays are value types. If you don't know what this means, see this article.