Guid.Parse () or the new Guid () - What's the difference?

Question

What is the difference between these two ways of converting a string in System.Guid ? Is there a reason for choosing one over the other?

 var myguid = Guid.Parse("9546482E-887A-4CAB-A403-AD9C326FFDA5"); 

or

 var myguid = new Guid("9546482E-887A-4CAB-A403-AD9C326FFDA5"); 

Answer 1

A quick glance at the reflector shows that both are pretty much equivalent.

 public Guid(string g) { if (g == null) { throw new ArgumentNullException("g"); } this = Empty; GuidResult result = new GuidResult(); result.Init(GuidParseThrowStyle.All); if (!TryParseGuid(g, GuidStyles.Any, ref result)) { throw result.GetGuidParseException(); } this = result.parsedGuid; } public static Guid Parse(string input) { if (input == null) { throw new ArgumentNullException("input"); } GuidResult result = new GuidResult(); result.Init(GuidParseThrowStyle.AllButOverflow); if (!TryParseGuid(input, GuidStyles.Any, ref result)) { throw result.GetGuidParseException(); } return result.parsedGuid; } 

Answer 2

Use the most readable version. These two are implemented almost exactly the same.

The only real difference is that the constructor is initialized to Guid.Empty before trying to parse. However, the effective code is identical.

Moreover, if Guid comes from user input, then Guid.TryParse will be better than any option. If this Guid hardcoded and always valid, any of the above options is perfectly reasonable.

Answer 3

I have tried working on one million and Guid.Parse seems insignificant faster. This made 10-20 milisecods a difference of 800 milliseconds of total creation on my PC.

 public class Program { public static void Main() { const int iterations = 1000 * 1000; const string input = "63559BC0-1FEF-4158-968E-AE4B94974F8E"; var sw = Stopwatch.StartNew(); for (var i = 0; i < iterations; i++) { new Guid(input); } sw.Stop(); Console.WriteLine("new Guid(): {0} ms", sw.ElapsedMilliseconds); sw = Stopwatch.StartNew(); for (var i = 0; i < iterations; i++) { Guid.Parse(input); } sw.Stop(); Console.WriteLine("Guid.Parse(): {0} ms", sw.ElapsedMilliseconds); } } 

And the conclusion:

new guid (): 804 ms

Guid.Parse (): 791 ms

Answer 4

I would go with TryParse . This is no exception.