Iteration Methods

Introduction

I’ve been implementing numerical libraries in .NET and have come to some conclusions about iteration performance. My classes have to hold a large amount of data and be able to iterate through that data as quickly as possible. In order to compare various methods, I created a simple class called Data that encapsulates an array of doubles.

Method #1: Enumeration

Data implements IEnumerable. It contains GetEnumerator which returns its own DataEnumerator, an inner class.

…
  public IEnumerator GetEnumerator()
   {
     return new DataEnumerator( this );
   }
   
   internal class DataEnumerator : IEnumerator
   {
     private Data internal_ = null;
     private int index = -1;

     public DataEnumerator( Data data )
     {
       internal_ = data;
     }

     public object Current
     {
       get
       {
         return internal_.Array[index];
       }
     }

     public bool MoveNext()
     {
       index++;
       if ( index >= internal_.Array.Length )
       {
         return false;
       }
       return true;
     }

     public void Reset()
     {
       index = -1;
     }
   }
…