Any string input can have these many possible states
1) String is null
2) String is empty
3) String contains nothing but white space
4) String has some content
Till now, .NET had static method for string
which handled first two conditions for us.
Now with .NET 4 we have another static method
Basically it is equivalent to the following code,
return String.IsNullOrEmpty(input) || input.Trim().Length ==0 ;
but has performance improvement
because white-space characters are defined by the Unicode standard. The IsNullOrWhiteSpace method interprets any character that returns a value of true when it is passed to the Char.IsWhiteSpace method as a white-space character.
We must have implemented logic for this condition everywhere in our applications but addition of this useful inbuilt function is nice to have with some performance improvement !