Nullable and Pattern Matching

Nullable Value Types

A nullable value type can hold a normal value or null.

Nullable Value Types

NullableValueTypes.cs 
using System;

class Program
{
    static void Main()
    {
        int? score = ;
        bool hasScore = score.HasValue;
        int shown = score.GetValueOrDefault();

        Console.WriteLine($"hasScore={hasScore}");
        Console.WriteLine($"shown={shown}");
    }
}

using System;

class Program
{
    static void Main()
    {
        int? score = ;
        bool hasScore = score.HasValue;
        int shown = score.GetValueOrDefault();

        Console.WriteLine($"hasScore={hasScore}");
        Console.WriteLine($"shown={shown}");
    }
}

using System;

class Program
{
    static void Main()
    {
        int? score = ;
        bool hasScore = score.HasValue;
        int shown = score.GetValueOrDefault();

        Console.WriteLine($"hasScore={hasScore}");
        Console.WriteLine($"shown={shown}");
    }
}
nullable value A nullable value type uses `?`, such as `int?`, to allow `null`.