LINQ equivalent of foreach for IEnumerable

There is no ForEach extension for IEnumerable; only for List. So you could do

items.ToList().ForEach(i => i.DoStuff());

Alternatively, write your own ForEach extension:

public static void ForEach<T>(this IEnumerable<T> enumeration, Action<T> action)
{
    foreach(T item in enumeration)
    {
        action(item);
    }
}