How to compare two Dictionary objects and find items missing from each?

Question

_{Tuesday, February 15, 2011 10:39 PM}

I have two Dictionary collections (dictA and dictB) containing instances of an object, and I would like to find instances in dictA and not in dictB (and vice versa).  Is there a straightforward way to accomplish this without manually writing two for loops?

Thanks in advance

All replies (3)

_{Wednesday, February 16, 2011 12:08 AM ✅Answered | 1 vote}

Add, at the top of your C# file:

    using System.Linq;

"Intersect" and "Except" are extension methods defined on the Enumerable class, and will work on any type that implements IEnumerable<T>, including Dictionary<T,U>.Keys.

Reed Copsey, Jr. - http://reedcopsey.com
If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful".

_{Tuesday, February 15, 2011 10:44 PM | 1 vote}

To check against keys:

// var dictionaryA;
// var dictionaryB;

var intersection = dictionaryA.Keys.Intersect(dictionaryB.Keys);

var extraKeysInA = dictionaryA.Keys.Except(intersection);
var extraKeysInB = dictionaryB.Keys.Except(intersection);

Values could be done similarly.

Reed Copsey, Jr. - http://reedcopsey.com
If a post answers your question, please click "Mark As Answer" on that post and "Mark as Helpful".

_{Tuesday, February 15, 2011 11:55 PM}

There must be something I'm missing - when I look at the Keys property on my Dictionary<TKey, TValue> objects, the only methods I see are:

• CopyTo
• Count
• Equals
• GetEnumerator
• GetHashCode
• GetType
• ToString

There is no Intersect or Except method listed in intellisense. I'm using .NET 3.5 SP1