Listing 12.4: Declaring Versions of Various Value Types That Store null

Listing 12.4.cs

struct NullableInt
{
    /// <summary>
    /// Provides the value when HasValue returns true
    /// </summary>
    public int Value{ get; private set; }

    /// <summary>
    /// Indicates whether there is a value or whether
    /// the value is "null"
    /// </summary>
    public bool HasValue{ get; private set; }

    // ...
}

struct NullableGuid
{
    /// <summary>
    /// Provides the value when HasValue returns true
    /// </summary>
    public Guid Value{ get; private set; }

    /// <summary>
    /// Indicates whether there is a value or whether
    /// the value is "null"
    /// </summary>
    public bool HasValue{ get; private set; }

    ...
}
...