How to check if IEnumerable collection is empty?

Question

How to do that properly? When I am trying to do value != null nothing happend. But this will work if i will write value.Count() != 0 that will work. Is it other way to do that?

Jay Ant · Answer

Hi! Finaly I found a way how to check if it is empty. I have to use Any().

Vijaya Kadiyala · Answer

Hi Jat Ant, May be thats good idea. Thank you for your feed on our answers ;) Thanks -- Vijaya Kadiyala www.DotNetVJ.com

Jay Ant · Answer

To Niradhip I think I sow that example somewhere when I did my search to solve the problem, and as I stated in the first post this statement do not work. Compiler allow me to write that if ( value != null ), but when the page is running, it tells me – yes, it is true, it is not null, it is empty! To Vijaya I did like this if ( value != Enumerable .Empty Object >()) and with no success. In article it is used to create empty collection. I am perfectly happy when I checking value.Count(), but I think that is better to check if collection is empty. Or, may be it is better not to bother with this at all and do that checking in the way that is working?

Vijaya Kadiyala · Answer

Hi Check out the below link on Usage: http://msdn.microsoft.com/en-us/library/bb341042.aspx Thanks -- Vijaya Kadiyala www.DotNetVJ.com

Niradhip Chakraborty · Answer

DO treat a null reference ( Nothing in Visual Basic and nullptr in C++/CLI) and an empty collection or IEnumerable as equivalent. For example, the following constructor treats both a null an empty IEnumerable instance similar; they both result in an empty StringCollection . public class StringCollection : Collection string > { public StringCollection( IEnumerable string > items) { if (items != null ) // Correct { foreach ( string item in items) { Add(item); } } } } DO NOT return a null reference ( Nothing in Visual Basic and nullptr in C++/CLI) from an array, collection or IEnumerable property or method; return an empty instance instead. Similar to string properties , consumers of your class expect to be to enumerate over the returned enumerable instance without also needing to check for null.

Jay Ant · Answer

Thanks for the reply, but I can`t figure out how to use it. For example, I have a property public IEnumerable ObjectList { set { If(value.Count() != 0 Do something } } How to do that your way with Enumerable.Empty

Vijaya Kadiyala · Answer

You can check out the below property.. Enumerable .Empty Thanks -- Vijaya Kadiyala www.DotNetVJ.com

How to check if IEnumerable collection is empty?

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Answers (7)