add textbox value to list

Question

List<int> MyLottoNumbers = new List<int>();
MyLottoNumbers[0] = int.Parse(textBoxNum1.Text);

textBoxNum1 has a value of 5

This code gives the error

Index was out of range. Must be non-negative and less than the size of the collection.

Why ?

Answer 1

It's because your list is currently empty, so you can't set the first index to something (because it doesn't exist). If you did this:

List<int> MyLottoNumbers = new List<int>();
MyLottoNumbers.Add(int.Parse("5"));
MyLottoNumbers[0] = int.Parse("7");

it works, because that index has been set.

If you want to insert at the front, take this route:

List<int> MyLottoNumbers = new List<int>();
MyLottoNumbers.Insert(0, int.Parse(textBoxNum1.Text));