?? operator (null coalescing operator) - ablealias/MVC GitHub Wiki

It returns the left-hand operand if the operand is not null; otherwise, it returns the right-hand operand.

middleName = middleName ?? "";

If you try to assign a nullable value type to a non-nullable value type without using the ?? operator, you will generate a compile-time error.

        int? x = null;

        // Set y to the value of x if x is NOT null; otherwise,
        // if x == null, set y to -1.
        int y = x ?? -1;