#1,117 – foreach Requires IEnumerable Implementation

The foreach statement works on an object that implements IEnumerable<T> or IEnumerable.  It also works on an object whose type has a public GetEnumerator method that returns an IEnumerator<T> or IEnumerator.

Below, we’ve defined a new class that implements IEnumerable<T>.

    public class DogPack : IEnumerable<Dog>
    {
        private List<Dog> thePack;

        public DogPack()
        {
            thePack = new List<Dog>();
        }

        public void Add(Dog d)
        {
            thePack.Add(d);
        }

        // Remove arbitrary dog
        public void Cull()
        {
            if (thePack.Count == 0)
                return;

            if (thePack.Count == 1)
                thePack.RemoveAt(0);
            else
            {
                Random rnd1 = new Random();
                int indRemove = rnd1.Next(thePack.Count);
                thePack.RemoveAt(indRemove);
            }
        }

        // IEnumerable<T> implementation

        public IEnumerator<Dog> GetEnumerator()
        {
            return thePack.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }

We can now use foreach to iterate on an instance of this class.

            DogPack pack = new DogPack();
            pack.Add(new Dog("Lassie", 8));
            pack.Add(new Dog("Shep", 12));
            pack.Add(new Dog("Kirby", 10));
            pack.Add(new Dog("Jack", 15));
            pack.Cull();

            // Who's left?
            foreach (Dog d in pack)
                Console.WriteLine(d);

1117-001

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #1,117 – foreach Requires IEnumerable Implementation

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