Double question mark operator in C#

C# has a very neat coalesce operator (??). Here's a quick explanation.

(The following was taken from here)


For two nullable variables, a and b,


int? a = null;
int? b = 5;


If a is not null, return a.
If a is null, then return b only if b is not null.
If b is also null, then I want to return 10;


This logic is written as follows.


if(a != null)
return a;
if(b != null)
return b;
return 10;



Or it can be written as follows.

return (a != null ? a : (b != null ? b : 10));


Or it can also be written as follows.

return ((a ?? b) ?? 10);