Hack to avoid creating garbage by allocating very small arrays in C# - emulating an array with a struct

ByValueArray.cs

// Hack to avoid creating lots of garbage by creating long[] arr = new long[2];
// There may be ways to implement this in a better way
// But all of them coming to my mind involve unsafe code
// Quickly breaks down when trying to emulate larger arrays
// -> then using switch() to select the right values
// -> Some compilers will optimize the switch() as a binary search, but still - Unsafe implementation can be O(1)!
struct ulong2
{
	ulong l0;
	ulong l1;

	public ulong this[ulong n]
	{
		get
		{
			return (n == 0) ? l0 : l1;
		}

		set
		{
			if (n == 0)
			{
				l0 = value;
			}
			else
			{
				l1 = value;
			}
		}
	}
}

static class Sample
{
	static void WithArray()
	{
		ulong[] arr = new ulong[2];
		
		for(int n=0; n<1024; n++)
		{
			arr[(n*3)%2]++;
		}
	}
	
	static void WithoutArray()
	{
		ulong2 arr = new ulong2();
		
		for(int n=0; n<1024; n++)
		{
			arr[(n*3)%2]++;
		}
	}
	
	public static void Main()
	{
		// many bytes garbage
		for(int n=0; n<1000; n++)
		{
			WithArray();
		}
		
		// Zero garbage
		for(int n=0; n<1000; n++)
		{
			WithoutArray();
		}
	}
}