#207 – Nullable Types

Because value types can’t normally represent null values, C# includes nullable types–types that can represent their normal range of values or represent a null value.

Any value type can be used as a nullable type by adding a trailing ? to the type name.

            int i = 12;   // regular int, can't be null

            int? j = 22;  // Nullable int, can be null
            j = null;     // Can also be null

Here are some other examples of nullable types.  In each case, we can set the variable’s value to null, which means that the variable doesn’t have a value that falls within the range of the corresponding type.

            double? r = null;
            bool? thisIsFalse = null;
            Mood? myMood = null;

Image may be NSFW.
Clik here to view.

Image may be NSFW.
Clik here to view.