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();

}