array example

test.cs

using System;

namespace Foo
{
	class Program
	{
		public static void Main(string[] args)
		{
			const int TestSize = 1000000;
			
			// guess which is faster and by approx. how much
			// then guess why
			
			var firstCase = new Foo[TestSize];
			var secondCase = new Bar[TestSize];
			
			for (int i = 0; i < TestSize; i++)
				secondCase[i].Value = firstCase[i] = new Foo();
			
			// Is this faster?
			for (int i = 0; i < TestSize; i += 50)
			{
				var tmp = new Foo[50];
				for (int j = 0; j < 50; j++)
				{
					tmp[j] = firstCase[i + j];
					tmp[j].X += 7;
				}
			}
			
			// Or this?
			for (int i = 0; i < TestSize; i += 50)
			{
				var tmp = new Bar[50];
				for (int j = 0; j < 50; j++)
				{
					tmp[j] = secondCase[i + j];
					tmp[j].Value.X += 11;
				}
			}
			
		}
	}
	
	class Foo
	{
		public int X, Y;
	}
	
	struct Bar
	{
		public Foo Value;
	}
}