Getting a list of string values from this c# function:

Question

I have been trying to get my head around this but it hasn't been working:

I've gotten this function from http://fir3pho3nixx.blogspot.com/2011/01/recursion-cross-product-of-multiple.html where it returns a list but I can't seem to read the values within each object in the list.

Here is the function in question:

    private static List<object> GetCrossProduct(object[][] arrays)
    {
        var results = new List<object>();
        GetCrossProduct(results, arrays, 0, new object[arrays.Length]);
        return results;
    }

    private static void GetCrossProduct(ICollection<object> results, object[][] arrays, int depth, object[] current)
    {
        for (var i = 0; i < arrays[depth].Length; i++)
        {
            current[depth] = arrays[depth][i];
            if (depth < arrays.Length - 1)
                GetCrossProduct(results, arrays, depth + 1, current);
            else
                results.Add(current.ToList());
        }
    }

Why would it return something your function has no return type and neither an out parameter.. it will always return as new List<object>() — V4Vendetta
– V4Vendetta, Commented Jul 4, 2011 at 5:11
Can you be more clear? What is the problem? Are you calling GetCrossProduct()? What argument are you passing it? — user122211
– user122211, Commented Jul 4, 2011 at 5:14
It's a recursive function when you need to return a cross product of a string[][] array. — kawai
– kawai, Commented Jul 4, 2011 at 5:14
The list returns what appears of a list of objects (and each object has the strings I need) ex: dl.dropbox.com/u/49200/List_Object.png I am having a lot of trouble pulling the values within the object (John, Red, Apple) — kawai
– kawai, Commented Jul 4, 2011 at 5:17
what is the purpose of passing current on the recursive call? looks like it should hold all elements of array[depth], isn't it? — NirMH
– NirMH, Commented Jul 4, 2011 at 5:32

user122211 · Accepted Answer · 2011-07-04 05:30:50Z

1

You are having problem because you are probably expecting a linear List, when it is actually a List of Lists.

To access elements within your result, you need to do something like this:

var resultingList = GetCrossProduct(blargh); // where blargh is the array you passed in
foreach (IList<object> innerList in resultingList)
{
    foreach (var listValue in innerList)
    {
        // listValues should be the individual strings, do whatever with them
        // e.g.
        Console.Out.WriteLine(listValue);
    }
}

The reason for this is because of the line:

results.Add(current.ToList());

Which creates a new list and adds it to the result list.

answered Jul 4, 2011 at 5:30

user122211

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1 Comment

kawai Over a year ago

Wow thanks so much, I see that now. The recursive function is adding the results in a new list within the list that's being returned. Thanks again for your help.

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