c# - How to count the number of occurences of a string in a ReadOnlyCollection field

Question

I have a ReadOnlyCollection of a Smartcard type from Microsoft.Clm.Shared.Smartcards namespace.

one of the fields/parameters of the smartcard object is AssingnedUserName.

I need to be able to count how many times a smartcard with the same username exist in the list,

something like:

[Pseudo Code]
int count = (smartcardCollection.AssignedUserName == my String).Count().

I tried to use the ReadOnlyCollection.Tolist() method, but I couldn't find the correct syntax to make it work.

I also found many examples but non for a ReadOnlyCollection object !

what is the best practice for achieving this ?

thanks

David.

[`Enumerable.Count` takes a predicate](https://msdn.microsoft.com/library/bb535181). See the examples. — Jeroen Mostert, Jun 26 '17 at 08:18
David, can you please mention data type of smartcardCollection? — mhdnp1234, Jun 26 '17 at 08:25
simple lambda sentence: `int Givaaty = smartcardCollection.Where(s => s.AssignedUserName == Rotem).Count();` — Jonathan Applebaum, Jun 26 '17 at 08:32

Tim Schmelter · Answer 1 · 2017-06-26T08:41:49.697

2

You just need to use the overload of Count or Where ... Count:

int count = smartcardCollection.Count(s => s.AssignedUserName == my String);

or

int count = smartcardCollection.Where(s => s.AssignedUserName == my String).Count();

edited Jun 26 '17 at 08:41

answered Jun 26 '17 at 08:20

Tim Schmelter

score 2 · Accepted Answer · answered Jun 26 '17 at 08:20

2

just use this

int count = smartcardCollection.Count(s=>s.AssignedUserName == my String);

LINQ Count it takes a function to test each element for a condition

answered Jun 26 '17 at 08:20

BRAHIM Kamel

2 Answers2