Question

I have this IEnumerable :

IEnumerable<MyObject>

and I need to order the list of the MyObject randomly. Do I need to cast into an ArrayList?

Or I can do it directly? Thanks

EDIT

this is my actual random order function :

IList<ArchiePacchettoOfferta> list = new List<ArchiePacchettoOfferta>(m_oEnum);
for (int i = 0; i < list.Count; ++i)
{
    HttpContext.Current.Response.Write(list[i].Titolo + "<br />");
}

Random rnd = new Random();
for (int i = 0; i < list.Count; ++i)
{
    int swapIndex = rnd.Next(i + 1);
    ArchiePacchettoOfferta tmp = list[i];
    list[i] = list[swapIndex];
    list[swapIndex] = tmp;
}

for (int i = 0; i < list.Count; ++i)
{
    HttpContext.Current.Response.Write(list[i].Titolo + "<br />");
}

it orders the list in the same way every time 🙁

Answer 1

Enumerators allow “iterated” access only. Thus, there is no possibility to access the elements randomly or in a sorted way. You have to read the enumerated values and (temporarily) store them in another list for which you can apply your (random) sorting algorithm.

[edit] Example:

List<MyObject> list = new List<MyObject>( my_enumerable );
Random rnd = new Random(/* Eventually provide some random seed here. */);
for (int i = list.Count - 1; i > 0; --i)
{
    int j = rnd.Next(i + 1);
    MyObject tmp = list[i];
    list[i] = list[j];
    list[j] = tmp;
}
my_enumerable = list;

(I have not tested the example code.)