How can I return an empty IEnumerable

Question

Given the following code and the suggestions given in this question  I ve decided to modify this original method and ask if there are any values in the IEnumarable return it  if not return an IEnumerable with no values   Here is the method   public IEnumerable lt Friend gt  FindFriends                           Many thanks to Rex-M for his help with this one                https   stackoverflow com users 67 rex-m              return doc Descendants  user   Select user   gt  new Friend                               ID   user Element  id   Value                  Name   user Element  name   Value                  URL   user Element  url   Value                  Photo   user Element  photo   Value                             Since everything is inside the return statement  I don t know how I could do this  Would something like this work   public IEnumerable lt Friend gt  FindFriends                           Many thanks to Rex-M for his help with this one                https   stackoverflow com users 67 rex-m             if  userExists                                return doc Descendants  user   Select user   gt  new Friend                                       ID   user Element  id   Value                      Name   user Element  name   Value                      URL   user Element  url   Value                      Photo   user Element  photo   Value                                               else                                return new IEnumerable lt Friend gt                               The above method doesn t work  and in fact it s not supposed to  I just feel it illustrates my intentions  I feel I should specify that the code doesn t work because you can t create an instance of an abstract class   Here is the calling code  I don t want it to receive a null IEnumerable at any time   private void SetUserFriends IEnumerable lt Friend gt  list                        int x   40              int y   3                foreach  Friend friend in list                                FriendControl control   new FriendControl                    control ID   friend ID                  control URL   friend URL                  control SetID friend ID                   control SetName friend Name                   control SetImage friend Photo                    control Location   new Point x  y                   panel2 Controls Add control                    y   y   control Height   4                              Thank you for your time

User · Answer

public IEnumerable lt Friend gt  FindFriends         return userExists   doc Descendants  user   Select user   gt  new Friend                       ID   user Element  id   Value              Name   user Element  name   Value              URL   user Element  url   Value              Photo   user Element  photo   Value             new List lt Friend gt

User · Answer

You could return Enumerable Empty lt T gt

User · Answer

You can use list    Enumerable Empty lt Friend gt     or have FindFriends return Enumerable Empty lt Friend gt

User · Answer

As for me  most elegant way is yield break

User · Answer

I think the simplest way would be    return new Friend 0     The requirements of the return are merely that the method return an object which implements IEnumerable lt Friend gt    The fact that under different circumstances you return two different kinds of objects is irrelevant  as long as both implement IEnumerable

User · Answer

That s of course only a matter of personal preference  but I d write this function using yield return   public IEnumerable lt Friend gt  FindFriends           Many thanks to Rex-M for his help with this one        http   stackoverflow com users 67 rex-m     if  userExists                foreach var user in doc Descendants  user                          yield return new Friend                                       ID   user Element  id   Value                      Name   user Element  name   Value                      URL   user Element  url   Value                      Photo   user Element  photo   Value

[c#] How can I return an empty IEnumerable?

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