what does array.length - 1 do in C# code example

Example 1: c# length of array

// declares a 1D Array of string. 
string[] weekDays; 
// allocating memory for days. 
weekDays = new string[] {"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"};
// Display length of array.
Console.Write(weekDays.Length);

Example 2: 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;