How to convert object[] to a more specifically typed array

Question

This would be pretty straight forward if I knew the types at compile time or if it was a generic parameter, because I could do something like myArray.Cast<T>() But what I actually have is essentially this. I do not have a known type or generic parameter. I have a System.Type variable.

// could actually be anything else
Type myType = typeof(string);  

// i already know all the elements are the correct types
object[] myArray = new object[] { "foo", "bar" }; 

Is there some kind of reflection magic I can do to get a string[] reference containing the same data? (where string isn't known at compile time)

Answer 1

It's not really a cast as such (I'm allocating a new array and copying the original), but maybe this can help you out?

Type myType = typeof(string);
object[] myArray = new object[] { "foo", "bar" };

Array destinationArray = Array.CreateInstance(myType, myArray.Length);
Array.Copy(myArray, destinationArray, myArray.Length);

In this code, destinationArray will be an instance of string[] (or an array of whatever type myType was).

Answer 2

You can't perform such a cast, because the arrays object[] and string[] are actually different types and are not convertible. However, if you wanted to pass different such types to a function, just make the parameter IEnumerable. You can then pass an array of any type, list of any type, etc.

    // Make an array from any IEnumerable (array, list, etc.)
    Array MakeArray(IEnumerable parm, Type t)
    {
        if (parm == null)
            return Array.CreateInstance(t, 0);
        int arrCount;
        if (parm is IList)     // Most arrays etc. implement IList
            arrCount = ((IList)parm).Count;
        else
        {
            arrCount = 0;
            foreach (object nextMember in parm)
            {
                if (nextMember.GetType() == t)
                    ++arrCount;
            }
        }
        Array retval = Array.CreateInstance(t, arrCount);
        int ix = 0;
        foreach (object nextMember in parm)
        {
            if (nextMember.GetType() == t)
                retval.SetValue(nextMember, ix);
            ++ix;
        }
        return retval;
    }