Convert IEnumerable<int> to int[]

Use the .ToArray() extension method if you're able to use System.Linq

If you're in .Net 2 then you could just rip off how System.Linq.Enumerable implements the .ToArray extension method (I've lifted the code here almost verbatim - does it need a Microsoft®?):

struct Buffer<TElement>{    internal TElement[] items;    internal int count;    internal Buffer(IEnumerable<TElement> source)    {        TElement[] array = null;        int num = 0;        ICollection<TElement> collection = source as ICollection<TElement>;        if (collection != null)        {            num = collection.Count;            if (num > 0)            {                array = new TElement[num];                collection.CopyTo(array, 0);            }        }        else        {            foreach (TElement current in source)            {                if (array == null)                {                    array = new TElement[4];                }                else                {                    if (array.Length == num)                    {                        TElement[] array2 = new TElement[checked(num * 2)];                        Array.Copy(array, 0, array2, 0, num);                        array = array2;                    }                }                array[num] = current;                num++;            }        }        this.items = array;        this.count = num;    }    public TElement[] ToArray()    {        if (this.count == 0)        {            return new TElement[0];        }        if (this.items.Length == this.count)        {            return this.items;        }        TElement[] array = new TElement[this.count];        Array.Copy(this.items, 0, array, 0, this.count);        return array;    }}

With this you simply can do this:

public int[] ToArray(IEnumerable<int> myEnumerable){  return new Buffer<int>(myEnumerable).ToArray();}

Call ToArray after a using directive for LINQ:

using System.Linq;...IEnumerable<int> enumerable = ...;int[] array = enumerable.ToArray();

This requires .NET 3.5 or higher. Let us know if you're on .NET 2.0.

IEnumerable<int> i = new List<int>{1,2,3};var arr = i.ToArray();