C# Convert object of type array to T, where T is an array?

Question

It'd be really good if I could get an object to array conversion working.

Steps:

1. We get passed an array from an external source. The array is boxed in an object. Typically the object is an int[] or a double[], but we normally want double[].
2. Convert it to an array of Type T.
3. return the converted type.

For starters, this works fine

double[] r=Array.ConvertAll<int,double>((int[])o,Convert.ToDouble)

but this doesn't (assume that T is "double") e.g. double[] R=getValue(o);

public T[] getValue<T>(object o){
// ... some logic...
return (T[])Array.ConvertAll<int,double>((int[])o,Convert.ToDouble)

Is there a where constraint that can be used? Array is a "Special Object", so we can't use that as a constraint.

Is this possible in .net without resorting to IL? Is it possilbe if we do resort to IL?

thanks, -Steven

Solution 1

This worked for me:

public T[] GetValue<T>(object o)
{
        Converter<int, T> c = new Converter<int, T>(input => (T)System.Convert.ChangeType(input, typeof(T)));
        return (T[])Array.ConvertAll<int, T>((int[])o, c);
}

I hope this helps!

Solution 2

Try this:

public T[] getValue<T>(object o)
{
    return (T[])Convert.ChangeType(o, typeof(T[]));
}

Use like this:

object doubleArr = new Double[] {1.3, 1.5, 1.7};
var returnedValue = getValue<double>(doubleArr);

Note that if you pass in the wrong type for the template, it will fail at run time