using System;

using System.Collections.Generic;

public class Program

{

    // see: https://stackoverflow.com/questions/51044334/c-how-can-a-iterator-loop-be-made-generic

​

    // Answer 1:

    // The downside is that you need to provide your increment 

    // func and you can pass any type implementing 

    // IComparable.Usage: var xd = Numbers<int>(1, 5, x => { x++; return x; });

    public static IEnumerable<T> Numbers<T>(T a, T b, Func<T, T> increment) 

    where T : struct, IComparable 

    { 

        var i = a; while (i.CompareTo(b) < 0) 

        { 

            yield return i; i = increment(i); 

        } 

    }

​

    // Answer 2:

    // Idea without passing increment function but can cause runtime error 

    // if increment is not implemented: 

    public static IEnumerable<T> Numbers<T>(T a, T b)

    where T : struct, IComparable

    {

        dynamic i = a; while (i.CompareTo(b) < 0)

        {

            yield return i; i++;

        }

    }

    public static void Main()

    {

        // implicit increment:

        Numbers<double>(1, 5).Dump();

        // explicit increment (+1), example 1:

        Numbers<int>(1, 5, x => {x++; return x;}).Dump();

        // explicit increment (+0.75), example 2:

        Numbers<float>((float)1.5, (float)7.5, x => { x += (float)0.75; return x; }).Dump();

​

    }

}

​

​