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  1. using System;
  2. using System.Collections.Generic;
  3. using System.Diagnostics;
  4. using System.Linq;
  5.  
  6. namespace ElementAtOrIndex
  7. {
  8.     class Program
  9.     {
  10.         // Declare/initialize static variables.
  11.         static Stopwatch timer = new Stopwatch();
  12.         static List<long> ElementAtTimes = new List<long>();
  13.         static List<long> IndexTimes = new List<long>();
  14.  
  15.         static void Main(string[] args)
  16.         {
  17.             // Declare/initialize variables.
  18.             int[] array;
  19.             int count = 1000000;
  20.             int iterations = 100;
  21.  
  22.             // Just initializes a list with elements from 0 to count.
  23.             // Slower than for loops, but pithy for an example on SO.
  24.             List<int> list = Enumerable.Range(0, count).ToList<int>();
  25.  
  26.             // Assert that both methods are equal.
  27.             for (int i = 0; i < list.Count; i++)
  28.             {
  29.                 if (list.ElementAt(i) != list[i])
  30.                 {
  31.                     Console.WriteLine("Both methods are not equal!");
  32.                     Environment.Exit(1);
  33.                 }
  34.             }
  35.             Console.WriteLine("Both methods are equal!");
  36.  
  37.             // Time ElementAt access *iterations* times by copying into an array.
  38.             for (int i = 0; i < iterations; i++)
  39.             {
  40.                 // [Re]initialize the array.
  41.                 array = new int[count];
  42.  
  43.                 // Start the timer.
  44.                 timer.Start();
  45.  
  46.                 for (int j = 0; j < list.Count; j++)
  47.                     array[j] = list.ElementAt(j);
  48.  
  49.                 // Explicitly stop the timer.
  50.                 timer.Stop();
  51.  
  52.                 // Note the time. 
  53.                 ElementAtTimes.Add(timer.ElapsedMilliseconds);
  54.             }
  55.  
  56.             // Time Index access *iterations* times by copying into an array.
  57.             for (int i = 0; i < iterations; i++)
  58.             {
  59.                 // [Re]initialize the array.
  60.                 array = new int[count];
  61.  
  62.                 // Start the timer.
  63.                 timer.Start();
  64.  
  65.                 for (int j = 0; j < list.Count; j++)
  66.                     array[j] = list[j];
  67.  
  68.                 // Explicitly stop the timer.
  69.                 timer.Stop();
  70.  
  71.                 // Note the time. 
  72.                 IndexTimes.Add(timer.ElapsedMilliseconds);
  73.             }
  74.  
  75.             // Output times.
  76.             Console.WriteLine("Average time for ElementAt access iteration: {0} ms", ElementAtTimes.Average());
  77.             Console.WriteLine("Average time for Index access iteration: {0} ms", IndexTimes.Average());
  78.  
  79.             Console.ReadLine();
  80.         }
  81.     }
  82. }
  83.  
Success #stdin #stdout 4.17s 66944KB
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Standard input is empty
stdout
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Both methods are equal!
Average time for ElementAt access iteration: 1334.65 ms
Average time for Index access iteration: 3254.34 ms
https://ideone.com/H0A2X
language:
C# (gmcs 5.20.1)
created:
12 years ago
visibility:
secret

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