String.Empty vs “” vs String. IsNullOrEmpty

I was reading up on this recently and a couple of interesting points came to light:

myString = “” creates a new instance of type String.

myString = String.Empty does not.

The key item is doing comparisons. Here’s some sample test code:

  
  class Program { 
  static void Main(string[] args) 
  { 
  String myString = "";
 long a, b, c, d, e, f;
 Console.WriteLine("Method 1...");
 a = DateTime.Now.Ticks;
 for (int index = 0; index < 100000000; index++) 
 { 
  bool isEmpty = myString == "";
 } 
 b = DateTime.Now.Ticks;
 Console.WriteLine("Method 2...");
 c = DateTime.Now.Ticks;
 for (int index = 0; index < 100000000; index++) 
 { 
  bool isEmpty = myString.Length == 0;
 } 
 d = DateTime.Now.Ticks;
 Console.WriteLine("Method 3...");
 e = DateTime.Now.Ticks;
 for (int index = 0; index < 100000000; index++) 
 { 
  bool isEmpty = String.IsNullOrEmpty(myString);
 } 
 f = DateTime.Now.Ticks;
 var Method1 = b - a;
 var Method2 = d - c;
 var Method3 = f - e;
 Console.WriteLine("Method 1: bool isEmpty = myString == \"\" took {0} ticks", Method1);
 Console.WriteLine("Method 2: bool isEmpty = myString.Length == 0; took {0} ticks", Method2);
 Console.WriteLine("Method 3: bool isEmpty = String.IsNullOrEmpty(myString) took {0} ticks", Method3);
 Console.Read();
 } 
 } 

The results:

Method 1: bool isEmpty = myString == "" took 4836000 ticks
Method 2: bool isEmpty = myString.Length == 0; took 2340000 ticks
Method 3: bool isEmpty = String.IsNullOrEmpty(myString) took 3744000 ticks

Bottom Line? The consensus among at least 4 or 5 expert Tweeters who commented was, IsNullOrEmpty is worth the extra ticks to test for null, even with 10 million iterations in the test!

Note: At the request of Todd Spatafore, I did a Visual Studio 2010 .NET 4.0 app that adds “String.IsNullOrWhitespace”. It performed the worst of all. You can download the VS2010 test solution here:

N.B. Jeremy commented to try:

bool isEmpty = (myString == null || myString.Length == 0);

I did this and it actually ran faster than bool isEmpty =myString.Length == 0;

so you could use this and achieve the need to test for null, and still be the fastest of the three methods shown.