#1,060 – Explicit Conversions between Nullable Types

An implicit conversion exists between two nullable types if an implicit conversion exists between the corresponding value types.  For example:

int i = 12;
long l = i;  // implicit int to long
int? i2 = 12;
long? l2 = i2;  // implicit int? to long?

Similarly, an explicit conversion exists between two nullable types if an explicit conversion exists between the corresponding value types.

long l = 12;
int i = (int)l;  // explicit long to int
long? l2 = 12;
int? i2 = (int?)l2;  // explicit long? to int?

You can also convert between a nullable and non-nullable type, either implicitly or explicitly.  An explicit conversion is required when converting from a nullable type to a non-nullable type or when an explicit conversion is required by the underlying types.

            int? i3 = (int?)l;   // explicit long to int?
            long l3 = (long)i3;  // explicit int? to long