?? Coalesce for empty string?

Question

Something I find myself doing more and more is checking a string for empty (as in "" or null) and a conditional operator.

A current example:

s.SiteNumber.IsNullOrEmpty() ? "No Number" : s.SiteNumber; 

This is just an extension method, it's equivalent to:

string.IsNullOrEmpty(s.SiteNumber) ? "No Number" : s.SiteNumber; 

Since it's empty and not null, ?? won't do the trick. A string.IsNullOrEmpty() version of ?? would be the perfect solution. I'm thinking there has to be a cleaner way of doing this (I hope!), but I've been at a loss to find it.

Does anyone know of a better way to do this, even if it's only in .Net 4.0?

Answer 1

C# already lets us substitute values for null with ??. So all we need is an extension that converts an empty string to null, and then we use it like this:

s.SiteNumber.NullIfEmpty() ?? "No Number"; 

Extension class:

public static class StringExtensions {     public static string NullIfEmpty(this string s)     {         return string.IsNullOrEmpty(s) ? null : s;     }     public static string NullIfWhiteSpace(this string s)     {         return string.IsNullOrWhiteSpace(s) ? null : s;     } }