Question

I see that over on this question LINQy way to check if any objects in a collection have the same property value there is a request to say how to do something using LINQ to see if a property matches in a collection. However, is this the fastest reasonable process by which to do this? I will be deploying something that requires a certain amount of resource management, and I want the application to be as responsive as can be, without making the code terribly hard to decipher when someone else, or myself come back to it later.

Answer 1

However, is this the fastest reasonable process by which to do this?

I’d guess that a fast way (perhaps the fastest way) to do it might be to add all the objects into a Dictionary or a HashSet, using the property as the key field: a method like HashSet.Add has a return code which tells you whether this property value has already been added. For example:

static bool containsDuplicate(Container<Foo> fooCollection) {     //create the hash set     HashSet<Bar> hashSet = new HashSet<Bar>();     //for each object to be tested     foreach (Foo foo in fooCollection)     {         //get the interesting object property         Bar propertyValue = fooCollection.bar;         //see whather we've already seen this property value         if (!hashSet.Add(propertyValue))         {             //duplicate detected             return true;         }     }     //no duplicate detected     return false; }