Explain about IEnumerable..??

Question

Please explain about IEnumerable in easy way and why we need? List Yrs = new List (); Yrs.Add(1992); Yrs.Add(1993); Yrs.Add(1994); Yrs.Add(1996); Yrs.Add(1997); Yrs.Add(1998); // IEnumerable ienum = (IEnumerable )Yrs; foreach (int i in Yrs) { Console.WriteLine(i); } With out IEnumerable also foreach loop works what is the need?

Amit Mohanty · Answer

IEnumerable is an interface that defines one method, GetEnumerator which returns an IEnumerator interface. This allows readonly access to a collection then a collection that implements IEnumerable can be used with a for-each statement. For more info check the below link. https://www.c-sharpcorner.com/UploadFile/0c1bb2/ienumerable-interface-in-C-Sharp/ https://www.dotnetperls.com/ienumerable https://www.claudiobernasconi.ch/2013/07/22/when-to-use-ienumerable-icollection-ilist-and-list/

Jayanth Reddy · Answer

foreach statement works only for those which have a definition for "get enumerator" as public. By Default all the collections were implemented from IEnumerable.So by default all the collections contains "get enumerator". From your above example as u were making use of a list,right click on the list,goto its definition,check for its get enumerable method. So you can make use of for eachloop directly in your example as it contains get enumerator. But in some situations you need to create some user defined class which should act as a collection.At that situation foreach loop doesnt work as "As it doesn't contain get Enumerator". So you have to implement IEnumerator for your class as IENumerator contains GetEnumerator method sothat you can make use of foreach loop. Refer this:https://www.youtube.com/watch?v=zyhGO4GXTQI&list=PLVlQHNRLflP-jc5Fbhfdhzv52AWYq836j&index=52

Amit Kumar · Answer

Hi, If you want to know more about Ienumerable. Please go through the below link it will help you. https://www.c-sharpcorner.com/article/difference-between-ienumerator-vs-ienumerable/