## Simple array (1 dimension) An array is a vector in a collection To declare an array we use : ```csharp public static void Main() { int[] vect = new int[4] // Declare a vector of 4 elements (from 0 to 3) vect[3] = 22; Console.WriteLine($"b = {b}"); Console.WriteLine($"{vect[3]}"); } ``` The result will be: ```bash b = 0 22 ``` We see that an array start from $0$ to $n-1$ ## Complex array (x dimension) To create a vect with multiple dimension, we just have to declare an array and add a brackets to define multiple dimension ```csharp // First version public static void Main() { int[,] mat = new int[12, 9] // Declare an array of two dimensions mat with default value for [0] mat[3, 4] = 12; } // Second version public static void Main() { int[,] mat = { { 2, 3 }, { 4, 5 } }; int a = mat[1, 0]; } ``` To display a matrice we will use: ```csharp public static void Main() { int[,] mat = { { 2, 3 }, { 4, 5 } }; int a = mat[1, 0]; for (int x = 0; x < math.GetLenght(...); x++) { for (int y = 0; y < math.GetLenght(...); y++) { Console.WriteLine(mat[x, y]) } } } ```