/* Enter a integer * The program tests for speed three methods * for creating an array of integers. Array * - stores a sequence of integers from 1 to * the number entered by the user */ using System; using System.Collections.Generic; using System.Linq; using System.Diagnostics; using static System.Console; namespace SoloLearn { class Program { static void Main(string[] args) { Int32.TryParse(ReadLine(), out int num); int i = GetIndex(num); Stopwatch s1 = Stopwatch.StartNew(); List l = _List(num); s1.Stop(); Stopwatch s2 = Stopwatch.StartNew(); IEnumerable e = _Enumerable(num); s2.Stop(); Stopwatch s3 = Stopwatch.StartNew(); int[] a = _Array(num); s3.Stop(); WriteLine($"Creating the sequence of integers 0..{num}"); WriteLine(new String('-', 34)); WriteLine("|Execution time of | milliseconds|"); WriteLine(new String('-', 34)); WriteLine($"|{"List",8}{"|",11}{s1.Elapsed.TotalMilliseconds,9}{"|",5}"); WriteLine($"|{"IEnumerable",15}{"|",4}{s2.Elapsed.TotalMilliseconds,9}{"|",5}"); WriteLine($"|{"Array",9}{"|",10}{s3.Elapsed.TotalMilliseconds,9}{"|",5}"); WriteLine(new String('-', 34)); Console.WriteLine(); /////////*** 2 ***//////// Stopwatch s11 = Stopwatch.StartNew(); int one = _ListGet(l, i); s11.Stop(); Stopwatch s22 = Stopwatch.StartNew(); int two = _EnumerableGet(e, i); s22.Stop(); Stopwatch s33 = Stopwatch.StartNew(); int three = _ArrayGet(a, i); s33.Stop(); WriteLine($"Get the element at a index {i}"); WriteLine(new String('-', 34)); WriteLine("|Execution time of | milliseconds|"); WriteLine(new String('-', 34)); WriteLine($"|{"List",8}{"|",11}{s11.Elapsed.TotalMilliseconds,9}{"|",5}"); WriteLine($"|{"IEnumerable",15}{"|",4}{s22.Elapsed.TotalMilliseconds,9}{"|",5}"); WriteLine($"|{"Array",9}{"|",10}{s33.Elapsed.TotalMilliseconds,9}{"|",5}"); WriteLine(new String('-', 34)); } static List _List(int n) { List m1 = new List(n); for (int i = 0; i < n; i++) m1.Add(i); return m1; } static IEnumerable _Enumerable(int n) { IEnumerable m2 = Enumerable.Range(0, n); return m2; } static int[] _Array(int n) { int[] m3 = new int[n]; for (int i = 0; i < n; i++) m3[i] = i; return m3; } static int _ListGet(List l, int i) { return l[i]; } static int _EnumerableGet(IEnumerable e, int i) { return e.ElementAt(i); } static int _ArrayGet(int[] a, int i) { return a[i]; } static int GetIndex(int n) { Random r = new Random(); return r.Next(0, n); } } }

Which collection is fastest?