Snippets in C#: More ways to check for NULL

breakdown.cs

// Option B: Checks if is NOT null
if (dog?.breed is { }) return dog.breed;

// Option C: Checks if is NOT null, then assigns to local variable "breedA"
if (dog?.breed is { } breedA) return breedA;

// Option D: Uses property pattern to check on object and return props as variables
if (dog?.breed is { Length: var lengthA } breedB) return $"{breedB} ({lengthA} characters long)";

dog.cs

public class Dog
{
	public string breed { get; set; }
}

main.cs

public class Dog
{
	public string breed { get; set; }
}

public class Program
{
	public static void Main()
	{
		TestNull();
		TestNotNull();
	}
	
	static void TestNull()
	{
		Dog dog = new Dog();
		string breed = GetBreed(dog);
		
		Console.WriteLine("TestNull: " + breed);
	}
	
	static void TestNotNull()
	{
		Dog dog = new Dog { breed = "american pitbull" };
		string breed = GetBreed(dog);
		
		Console.WriteLine("TestNull: " + breed);
	}
	
	static string GetBreed(Dog? dog)
	{
		// Option A: Checks if is null
		// if (dog?.breed is null) return "unknown";
		
		// Option B: Checks if is NOT null
		// if (dog?.breed is { }) return dog.breed;
		
		// Option C: Checks if is NOT null, then assigns to local variable "breedA"
		// if (dog?.breed is { } breedA) return breedA;
		
		// Option D: Uses property pattern to check on object and return props as variables
		// if (dog?.breed is { Length: var lengthA } breedB) return $"{breedB} ({lengthA} characters long)";
		
		// Option E: Property pattern as one-liner
		return dog?.breed is { Length: var lengthB } breedC
			? $"`{breedC}` ({lengthB} characters long)"
			: "Unknown Breed";
		
		// Unreachable Code
		// return dog.breed;
	}
}