What I did was write a IsNullOrBlank in a Helper Class.

the key is that you will want to test length because that is quicker than testing the string itself. is string == ""; sting.length == 0

Also want to test null before lenght. The idea is that if one is true then the if stops. If the first test is for lenght on a sting that is null you will get an error. So the order of the test is important because if buffer == null the other 'or' part of the if will not execute.

public class StringHelper
{
    public static bool IsNullOrBlank(string testBuffer)
    {
       if(testBuffer == null || testBuffer.Length == 0)
           return true;
       else
           return false;
    }
}

if(!StringHelper.IsNullOrBlank(buffer))
  buffer not null
else
  buffer is null

if(StringHelper.IsNullOrBlank(buffer))
  buffer is null
else
  buffer is not null


- g