Linq to search for objects and sum results

Question

I have a set of tasks that contain several fields, but more importantly. Duration type Int.

List<Task> tasks = new List<Task>; tasks.Add(new Task{Name= 'Task 1', Duration = 3 }); tasks.Add(new Task{Name= 'Task 2', Duration = 2}); tasks.Add(new Task{Name= 'Task 3', Duration = 1}); tasks.Add(new Task{Name= 'Task 4', Duration = 4}); 

Given the task, I want to find this task in the list, and then summarize everything that came before it. For instance. If I have the task "Task 3", then the result that I want is 5, that is, the tasks before "Task 3" are task 1 and Task 2 with a duration of 3 and 2, respectively, which is 5.

Hope this makes sense and someone can give an answer. Hoping to do this with linq, rather than just looping back.

Thanks in advance.

Answer 1

You can use the Linq TakeWhile extension method, followed by Sum :

 var result = tasks.TakeWhile(t => t.Name != "Task 3").Sum(x => x.Duration);