Which is Faster List.foreach or listString.GetEnumerator()

Question

I have written the following code to print the item values inside the list. Now I want to measure which one is faster as going forward I will have huge list to deal with. And please specify why you think that's better (if any evidences)

So how do I calculate the processing time? Is manually creating a bulky List is the only option?

  public void printMedod(string strPrintListVal)
        {
            Console.WriteLine(strPrintListVal);
        }


        static void Main(string[] args)
        {
            Program p1 = new Program();

            List<string> listString = new List<string> { "Rox","Stephens","Manahat","Lexus",":)"};
            listString.ForEach(p1.printMedod);
            Console.ReadKey();
        }

I can also do the same thing using GetEnumerator:

        static void Main(string[] args)
        {
            List<string> listString = new List<string> { "Rox","Stephens","Manahat","Lexus",":)"};
            var enumerator = listString.GetEnumerator();
            while (enumerator.MoveNext())
            {
                var pair = enumerator.Current;
                Console.WriteLine(pair);
            }
            Console.ReadKey();
        }

don't use the `ForEach` extension, whats wrong with a `foreach` loop? If you want to know which is faster, time them. — Jodrell, Jul 10 '12 at 08:54
Aside: `foreach obj in list` is actually inlined to a `while` using `GetEnumerator()` so those two should be equivalent. — dash, Jul 10 '12 at 08:57
*how do I calculate the processing time*, you can use a `Stopwatch` — V4Vendetta, Jul 10 '12 at 08:57
@Simsons :) well i meant [This Stopwatch](http://msdn.microsoft.com/en-us/library/system.diagnostics.stopwatch.aspx) but that was indeed funny — V4Vendetta, Jul 10 '12 at 09:05
The biggest performance between these two samples would likely be the use of `Program.printMedod` — Jodrell, Jul 10 '12 at 09:20
Old but relavent http://diditwith.net/PermaLink,guid,506c0888-8c5f-40e5-9d39-a09e2ebf3a55.aspx — Jodrell, Jul 10 '12 at 10:36

score 5 · Answer 1 · answered Jul 10 '12 at 09:02

5

I'd ForEach my way through the list, but I've been told a for loop is faster than anything else:

for(int i = 0;i < stringList.Length; i++)
{
    Console.WriteLine(stringList[i]);
}

answered Jul 10 '12 at 09:02

Alex

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I believe, if the underying type has a fast indexer then yes. Especially useful for arrays. – Jodrell Jul 10 '12 at 09:10

score 3 · Answer 2 · answered Jul 10 '12 at 09:02

3

You can use LinqPad, it displays an execution time

answered Jul 10 '12 at 09:02

saj

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score 1 · Answer 3 · edited May 23 '17 at 10:33

1

Neither is the best option here, just do

static void Main(string[] args)
{
    var stringList = new List<string> 
        { "Rox", "Stephens", "Manahat", "Lexus", ":)" };

    foreach(var s in stringList)
    {
        Console.WriteLine(s);
    }

    Console.ReadKey();
}

EDIT

use a StopWatch more info in this question

using System.Diagnotics;

var stopWatch = new StopWatch();

stopWatch.Start();

// Do somthing
// If somthing is really fast do lots of somthing

stopWatch.Stop();

// The duration is a TimeSpan in stopWatch.Elapsed;

edited May 23 '17 at 10:33

Community

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1

answered Jul 10 '12 at 09:00

Jodrell

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Thanks, but how do I get to know? Is there way we can measure the processing time – Simsons Jul 10 '12 at 09:03
As someone said in the comments above, that is inlined to a `while`-loop with `GetEnumerator()` so it's not faster then writing code using `GetEnumerator()` yourself. – Karl-Johan Sjögren Jul 10 '12 at 09:05
@Karl-JohanSjögren, agreed, but its not slower either but more common and therefore, I suggest, more readable. – Jodrell Jul 10 '12 at 09:13

Which is Faster List.foreach or listString.GetEnumerator()

3 Answers3