Question

foreach (Dictionary<string, object> dictionary in listOfDictionaries)
{
    if( object.Equals(dictionary, listOfDictionaries.Last() )
    {
        //Do something on last iteration of foreach loop.
    }
}

I realized fairly soon on that I wanted a reference equals, but it still brought up the question of how this code could not be hit. Does object.Equals not implicitly know how to compare two Dictionaries, and thus returns not equal?

Answer 1

There are a couple of ways the body of the if statement could not be hit in this scenario.

1. listOfDictionaries is an empty collection hence the if statement will never be tested.
2. listOfDictionaries could be a generated sequence which returns a new instance of Dictionary<string, object> every time it’s iterated and hence the elements do not have referential equality between iterations.

Could you give us a bit more context here? Perhaps show the type of listOfDictionaries?

Here’s an alternative solution that doesn’t require any extra allocations as would be incurred with .ToList

using (var e = listOfDictionaries.GetEnumerator()) {
  var hasMore = e.MoveNext();
  while (hasMore) {
    var dictionary = e.Current;
    ...
    hasMore = e.MoveNext();
    if (!hasMore) {
      // Inside this if block dictionary is the last item in listOfDictionaries
    }
  }
}