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CSharp · Console

/Program.cs

using System;
using System.Text;
using System.Diagnostics;

var (r0, dt0) = Tester(() => ConcaténerString("J'aime mon prof", 10_000));
var (r1, dt1) = Tester(() => ConcaténerStringBuilder("J'aime mon prof", 10_000));
if (r0 != r1)
{
   Console.WriteLine("Quelque chose de suspect s'est passé");
}
else
{
   Console.WriteLine($"string : {dt0} ms; StringBuilder : {dt1} ms");
}

static (T, long) Tester<T>(Func<T> f)
{
   var sw = new Stopwatch();
   sw.Start();
   T rés = f();
   sw.Stop();
   return (rés, sw.ElapsedMilliseconds);
}
static string ConcaténerString(string s, int n)
{
   string rés = "";
   for (int i = 0; i < n; ++i)
   {
      rés += s;
   }
   return rés;
}
static string ConcaténerStringBuilder(string s, int n)
{
   StringBuilder sb = new ();
   for (int i = 0; i < n; ++i)
   {
      sb.Append(s);
   }
   return sb.ToString();
}