Compare Two Arrays Of Different Lengths and Show Differences

Question

Problem:
I have two arrays that can possibly be different lengths. I need to iterate through both arrays and find similarities, additions, and deletions.

Answer 1

I wrote this a while back:

Usage:

foreach (var diff in Foo_Old.Diff(Foo_New)){
   Console.WriteLine ("{0} action performed on {1}",diff.DiffAction,diff.Value);
}

Implementation:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace LinqExtensions {

    enum DiffAction {
       Added,
       Removed,
       Same
    }

    class DiffPair {
        public T Value { get; set; }
        public DiffAction DiffAction { get; set; }
    }

    static class DiffExtension {
        public static IEnumerable> Diff
                 (
                     this IEnumerable original,
                     IEnumerable target 
                 ) {

            Dictionary results = new Dictionary();

            foreach (var item in original) {
                results[item] = DiffAction.Removed;
            }

            foreach (var item in target) {
                if (results.ContainsKey(item)) {
                    results[item] = DiffAction.Same;
                } else {
                    results[item] = DiffAction.Added;
                }
            }
            return results.Select(
                pair => new DiffPair {
                    Value=pair.Key, 
                    DiffAction = pair.Value
                });
        }
    }

}