what is the difference between list<> and dictionary<> in c#

Question

I have a strange doubt regarding list and dictionary in c#

In a list we add items to list by using the following method

using System.Collections.Gen         


        

Answer 1

List<> and Dictionary<,> - pretty different data structures which used for different purposes, List is simply a set of items and Dictionary is a set of key-value pairs.

Dictionary is pretty useful when you have a set of complex objects and want to have fast access by let's say ObjectName/ObjectId, in this case you create IDictionary where key would be ObjectId and Value would be an object itself.

Some differences:

• List persist order of the items, Dictionary does not
• List allow fast access by index
• List support built in QuickSort algorithm for fast data sorting
• Dictionary allows ~O(1) time complexity to access an item (value) by a key