using System;

using System.Collections.Generic;

public class Program

{

    public static List<int> nums = new List<int>(){1, 2, 3, 4, 5};

    public static void Main()

    {

        foreach(int i in Filter(3))

        {

            Console.WriteLine(i);

        }

        foreach(int i in FilterWithYieldReturn(3))

        {

            Console.WriteLine(i);

        }

        foreach(int i in RunningTotal())

        {

            Console.WriteLine(i);

        }

    }

    public static IEnumerable<int> Filter(int val)

    {

        List<int> tempList = new List<int>();

        foreach(int i in nums)

        {

            if(i > val)

                tempList.Add(i);

        }

        return tempList;

    }

    public static IEnumerable<int> FilterWithYieldReturn(int val)

    {

        foreach(int i in nums)

        {

            if(i > val)

                yield return i;

        }

    }

    public static IEnumerable<int> RunningTotal()

    {

        int total = 0;

        foreach(int i in nums)

        {

            total += i;

            yield return total;

        }

    }

}

​