Most advisable way of checking empty strings in C#

Question

What is the best way for checking empty strings (I\'m not asking about initializing!) in C# when considering code performance?(see code bel

Answer 1

Create an extension method for complete check:

public static bool IsEmpty(this string s)
{
  if(s == null) return true;
  return string.IsNullOrEmpty(s.Trim()); // originally only (s)
}

Sorry, not good code, fixed. Now this will tell you, if the string is empty or if is empty after trimming.