ForEach

public static IEnumerable<T> ForEach<T>(this IEnumerable<T> array, Action<T> act)
{
    foreach (var i in array)
        act(i);
    return array;
}

public static IEnumerable<T> ForEach<T>(this IEnumerable arr, Action<T> act)
{
    return arr.Cast<T>().ForEach<T>(act);
}

public static IEnumerable<RT> ForEach<T, RT>(this IEnumerable<T> array, Func<T, RT> func)
{
    var list = new List<RT>();
    foreach (var i in array)
    {
        var obj = func(i);
        if (obj != null)
            list.Add(obj);
    }
    return list;
}

string[] names = new string[] { "C#", "Java" };
names.ForEach(i => Console.WriteLine(i));

IEnumerable<int> namesLen = names.ForEach(i => i.Length);
namesLen.ForEach(i => Console.WriteLine(i));