Help on c# list

Hi,

I have a array of list & I am trying to add items to the array of list & getting object reference error. Could you see if anything wrong here.

         List<string>[] list = new List<string>[4];

   
        list[0].Add("test3");
        list[0].Add("test4");
 
        list[1].Add("test1");
        list[1].Add("test2");

      Messagebox.Show(list[0].ToArray());
     Messagebox.Show(list[1].ToArray());
r_pat72Asked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

anarki_jimbelSenior DeveloperCommented:
OK, you have created an array of lists but you haven't created lists in this array!
You have to create them explicitly.
0
anarki_jimbelSenior DeveloperCommented:
Try this:

        private void button2_Click(object sender, EventArgs e)
        {
            List<string>[] list = new List<string>[4];

            for (int i = 0; i < list.Length; i++)
            {
                list[i] = new List<string>();
            }

            list[0].Add("test3");
            list[0].Add("test4");

            list[1].Add("test1");
            list[1].Add("test2");

            //MessageBox.Show(list[0].ToArray().ToString());
            MessageBox.Show(list[1].ToArray().ToString());

            // see in output window:
            for (int i = 0; i < list.Length; i++)
            {
                int j = 0;
                List<string> lst = list[i];
                foreach (string s in lst)
                {
                    System.Diagnostics.Debug.WriteLine("List[" + i + "][" + j + "] = " + list[i][j]);
                    j++;
                }
            }
        }

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
r_pat72Author Commented:
Do I have to do something like this


List<string>[] list = new List<string>[4];

       list[0] =   new List<string>();
        list[0].Add("test3");
        list[0].Add("test4");
 
       list[1] =   new List<string>();
        list[1].Add("test1");
        list[1].Add("test2");

      Messagebox.Show(list[0].ToArray());
     Messagebox.Show(list[1].ToArray());
0
anarki_jimbelSenior DeveloperCommented:
Yes, you need to do that.
0
Bob LearnedCommented:
You should be able to use initializer syntax, like this:


            List<string>[] list = new List<string>[]
            {
                new List<string>{"test 1-1", "test 1-2", "test 1-3"},
                new List<string>{"test 2-1", "test 2-2", "test 2-3"}
            };

Open in new window

0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
C#

From novice to tech pro — start learning today.