Checking for string contents? string Length Vs Empty String

Question

Which is more efficient for the compiler and the best practice for checking whether a string is blank?

1. Checking whether the length of the string == 0

Answer 1

Assuming your question is .NET:

If you want to validate your string against nullity as well use IsNullOrEmpty, if you know already that your string is not null, for example when checking TextBox.Text etc., do not use IsNullOrEmpty, and then comes in your question.
So for my opinion String.Length is less perfomance than string comparison.

I event tested it (I also tested with C#, same result):

Module Module1
  Sub Main()
    Dim myString = ""


    Dim a, b, c, d As Long

    Console.WriteLine("Way 1...")

    a = Now.Ticks
    For index = 0 To 10000000
      Dim isEmpty = myString = ""
    Next
    b = Now.Ticks

    Console.WriteLine("Way 2...")

    c = Now.Ticks
    For index = 0 To 10000000
      Dim isEmpty = myString.Length = 0
    Next
    d = Now.Ticks

    Dim way1 = b - a, way2 = d - c

    Console.WriteLine("way 1 took {0} ticks", way1)
    Console.WriteLine("way 2 took {0} ticks", way2)
    Console.WriteLine("way 1 took {0} ticks more than way 2", way1 - way2)
    Console.Read()
  End Sub
End Module

Result:

Way 1...
Way 2...
way 1 took 624001 ticks
way 2 took 468001 ticks
way 1 took 156000 ticks more than way 2

Which means comparison takes way more than string length check.