Which loop is faster, while or for?

Question

You can get the same output with for and while loops:

While:

$i = 0;
while ($i <= 10){
  print $i.\"\\n\";
  $i++;
};
         


        

Answer 1

I also tried to benchmark the different kinds of loop in C#. I used the same code as Shane, but I also tried with a do-while and found it to be the fastest. This is the code:

using System;
using System.Diagnostics;


public class Program
{
    public static void Main()
    {
        int max = 9999999;
        Stopwatch stopWatch = new Stopwatch();

        Console.WriteLine("Do While Loop: ");
        stopWatch.Start();
        DoWhileLoop(max);
        stopWatch.Stop();
        DisplayElapsedTime(stopWatch.Elapsed);
        Console.WriteLine("");
        Console.WriteLine("");

        Console.WriteLine("While Loop: ");
        stopWatch.Start();
        WhileLoop(max);
        stopWatch.Stop();
        DisplayElapsedTime(stopWatch.Elapsed);
        Console.WriteLine("");
        Console.WriteLine("");

        Console.WriteLine("For Loop: ");
        stopWatch.Start();
        ForLoop(max);
        stopWatch.Stop();
        DisplayElapsedTime(stopWatch.Elapsed);
    }

    private static void DoWhileLoop(int max)
    {
        int i = 0;
        do
        {
            //Performe Some Operation. By removing Speed increases
            var j = 10 + 10;
            j += 25;
            i++;
        } while (i <= max);
    }

    private static void WhileLoop(int max)
    {
        int i = 0;
        while (i <= max)
        {
            //Performe Some Operation. By removing Speed increases
            var j = 10 + 10;
            j += 25;
            i++;
        };
    }

    private static void ForLoop(int max)
    {
        for (int i = 0; i <= max; i++)
        {
            //Performe Some Operation. By removing Speed increases
            var j = 10 + 10;
            j += 25;
        }
    }

    private static void DisplayElapsedTime(TimeSpan ts)
    {
        string elapsedTime = String.Format("{0:00}:{1:00}:{2:00}.{3:00}", ts.Hours, ts.Minutes, ts.Seconds, ts.Milliseconds / 10);
        Console.WriteLine(elapsedTime, "RunTime");
    }
}

and these are the results of a live demo on DotNetFiddle:

Do While Loop:
00:00:00.06

While Loop:
00:00:00.13

For Loop:
00:00:00.27