how to set up the size of an array c# code example

Example 1: how to declare an array lenght in c#

public int[] number = new int[2 /* the number here declares the lenght, not the index*/ ];
    int[1 /*this number here declares the index*/] = 69;

Example 2: add size to array C#

Array.Resize(ref arrayName, arrayName.Length + 4);