ObservableCollection.Remove - Cannot convert lambda expression to type because its not a delegate type
c#, c#-4.0
Solution
As the error message unclearly states, you can't do that. `ObservableCollection<T>` does not have a method that removes items that match a condition. (unlike `List<T>`, which has `RemoveAll()`)
Instead, you can loop backwards through the collection and call `Remove()`.
Problem
I stumbled across this very strange compiler behavior. I am trying to remove items from ObservableCollection based on some condition. Here is what I have in my code which throws error ``` public ObservableCollection<StandardContact> StandardContacts { get; set; } .... StandardContacts.Remove(s => s.IsMarked); //Compiler Error ``` The error is as follows ``` Error Cannot convert lambda expression to type 'RelayAnalysis_Domain.Entity.StandardContact' because it is not a delegate type ``` Surprisingly, the code below in the same method works ``` var deleteCount = StandardContacts.Where(s => s.IsMarked).Count(); //This Works ``` I already have following imports in my class ``` using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Data; using System.Data.Entity; ``` This question may turnout to be silly, but it has had my head scratching. Note: Even the Intellisence shows the same error