Loop through ArrayList of objects C#

Question

I'm trying to loop through an ArrayList of objects of type (people) so i created two classes :

Person.cs

using System;

namespace GenericTypes
{
    public class Person
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public int Age { get; set; }
        public DateTime DateTime { get; set; }

    }
}

People.cs

using System;
using System.Collections;
using System.Collections.Generic;

namespace GenericTypes
{
    public class People
    {
        public ArrayList GetNonGenericPeople()
        {
            var people = new ArrayList()
            {
                new Person() {FirstName = "Djerah", LastName = "Ahmed Rafik", Age = 23, DateTime = DateTime.Today},
                new Person() {FirstName = "Djerah", LastName = "Amjed Amir", Age = 11, DateTime = DateTime.Today},
                new Person() {FirstName = "Gadda", LastName = "Anoir", Age = 25, DateTime = DateTime.Today}

            };
            return people;
        }

        public  List<Person> GetGenericPeople()
        {
            var people = new List<Person>()
            {
                new Person() {FirstName = "Djerah", LastName = "Ahmed Rafik", Age = 23, DateTime = DateTime.Today},
                new Person() {FirstName = "Djerah", LastName = "Amjed Amir", Age = 11, DateTime = DateTime.Today},
                new Person() {FirstName = "Gadda", LastName = "Anoir", Age = 25, DateTime = DateTime.Today}

            };

            return people;
        }
    }
}

What i couldn't figure out is how to loop through GetNonGenericPeople() so can i output every object with it's properties

program.cs

namespace GenericTypes
{
    class Program
    {
        static void Main(string[] args)
        {
           var persons = new People();
            var p = persons.GetNonGenericPeople();

            foreach (var s in p)
            {
                Console.WriteLine(s);
            }
        }
    }
}

Dmitrii Bychenko · Accepted Answer · 2016-10-07 11:12:00Z

2

Try OfType<T>() Linq which filters out T instances; another option is Cast<T>() which tries to cast each item (and throw exception if cast fails)

 foreach (var s in p.OfType<Person>()) {
   ...
 }

edited Oct 7, 2016 at 11:12

answered Oct 7, 2016 at 11:10

Dmitrii Bychenko

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3 Comments

Dmitrii Bychenko Over a year ago

@D.AhmedRafik: you're welcome! However remember that ArrayList is obsolete class and List<Person> is a better choice for the collection.

D.AhmedRafik Over a year ago

One thing i didn't figure out is why we need to cast ArrayList to Generic List so we can access the properties of Person

Dmitrii Bychenko Over a year ago

ArrayList doesn't implement IEnumerable<Person> but IEnumerable only. It's possible that the ArrayList instance contians string, object, Form etc. items so we have either to filter out Person items via OfType<Person>() or cast items via Cast<Person>()

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