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  1. using System;
  2. using System.Collections.Generic;
  3. using System.Diagnostics;
  4. using System.Linq;
  5. using System.Text;
  6. using System.Text.RegularExpressions;
  7. using System.Threading.Tasks;
  8.  
  9. namespace RegexVsStrings
  10. {
  11.     class Program
  12.     {
  13.         static TimeSpan ProfileIt(Func<int> a)
  14.         {
  15.             const int numberOfRuns = 10;
  16.             a();
  17.  
  18.             int total = 0;
  19.             var sw = Stopwatch.StartNew();
  20.             for (int i = 0; i < numberOfRuns; i++)
  21.                 total += a();
  22.             sw.Stop();
  23.  
  24.             Console.WriteLine("Total result: " + total);
  25.  
  26.             return sw.Elapsed;
  27.         }
  28.  
  29.         static List<string> data;
  30.  
  31.         static Random r = new Random();
  32.  
  33.         static string RandomString()
  34.         {
  35.             var l = r.Next(2, 50);
  36.             return new string(Enumerable.Range(0, l).Select(_ => (char)('a' + r.Next(25))).ToArray());
  37.         }
  38.  
  39.         static Regex regex = new Regex(@"^music(?:(?>[^\.\n]+)|\.)*\.(?:mp3|wav)$", RegexOptions.Multiline | RegexOptions.Compiled);
  40.  
  41.         static int TestRegex()
  42.         {
  43.             var count = 0;
  44.             foreach (var s in data)
  45.                 if (regex.IsMatch(s))
  46.                     count++;
  47.             return count;
  48.         }
  49.  
  50.         static int TestStringCompare()
  51.         {
  52.             var count = 0;
  53.             foreach (var s in data)
  54.                 if (s.StartsWith("music") && (s.EndsWith("mp3") || s.EndsWith("wav")))
  55.                     count++;
  56.             return count;
  57.         }
  58.  
  59.         static void Main(string[] args)
  60.         {
  61.             data = Enumerable.Range(0, 500)
  62.                              .Select(n => new[]
  63.                                           {
  64.                                               "music" + RandomString() + "mp3",
  65.                                               "music" + RandomString() + "wav",
  66.                                               "trampampam" + RandomString() + "tralala",
  67.                                               "music" + RandomString() + "tralala",
  68.                                               "lalafa" + RandomString() + "mp3"
  69.                                           })
  70.                              .SelectMany(s => s)
  71.                              .ToList();
  72.  
  73.             var t1 = ProfileIt(TestRegex);
  74.             var t2 = ProfileIt(TestStringCompare);
  75.             Console.WriteLine("Regex: " + t1);
  76.             Console.WriteLine("String compare: " + t2);
  77.         }
  78.     }
  79. }
Success #stdin #stdout 0.69s 25848KB
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Standard input is empty
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Total result: 0
Total result: 10000
Regex: 00:00:00.0549839
String compare: 00:00:00.4220896
https://ideone.com/4Wk6rO
language:
C# (gmcs 5.20.1)
created:
8 years ago
visibility:
public

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