Speed: Collection vs. Dictionary

Permanently deleted user

25. November 2014 13:46

Is there any difference in the speed of traversing a Collection versus a Dictionary? Or checking an item exists in a Collection versus checking it exists in a Dictionary? In both instances I'd be checking for a string value.

Thanks

 

 

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  Berend Veldkamp

  25. November 2014 20:31

  It depends. Are those string values in the dictionary stored as key or as value?

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  Permanently deleted user

  26. November 2014 05:09

  As I only need to store the string values without a corresponding key or value the string values could be stored as either. As keys and values aren't ordered, is there a difference in speed?

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  Berend Veldkamp

  26. November 2014 16:35

  There is a difference: List.Contains() is slower than Dictionary.ContainsKey(), unless the searched item happens to be the first one in the list.

  I wrote a small test where I searched for the last item in a list of 5000. This resulted in ~6000 msec for 100,000 searches in a list, and 6 msec in a dictionary. A SortedSet<string> took ~300 msec.

  So unless you have a very large list, or want to search many items, you will hardly find a difference, and you shoud pick the solution that is the most readable/maintainable.

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