Question

There is the next task:
I need to check if input parameter (object) is array, then return array of input elements. For example I have input array like this:

int [] array = {1,2,3,4};

And method

  private object[] GetArray(object @from)
  {
  }

So, I need to check in this method that input variable is array and after return this array.
For checking I use

if(@from.GetType().IsArray)

And how to create array from object ??? Is it possible ?
Thanks.

Answer 1

If what you want to do is return @from as an object[] — if it is already an object[] — then the simplest way is just:

private object[] GetArray(object @from)
{
    return @from as object[] ?? new object[] { @from };
}

The above might look kind of confusing. Here’s how it works:

1. If @from is an object[] to begin with, it just returns that (typed as such).
2. Other wise, the expression @from as object[] evaluates to null. In this case, the null-coalescing operator (??) evaluates the following expression: new object[] { @from }.

So the result is that this method returns either the already existing object[] array, or an array of length 1 containing @from.

On the other hand, if you want to populate an object[] from the contents of @from, I’d do this:

private object[] GetArray(object @from)
{
    var objects = @from as IEnumerable;
    if (objects != null)
        return objects.Cast<object>().ToArray();

    return new object[] { @from };
}

As LukeH pointed out, you could also check to make sure @from is not a string, if you don’t want GetArray(string) to return an object[] containing char elements:

private object[] GetArray(object @from)
{
    var str = @from as string;
    if (str != null)
        return new object[] { str };

    var objects = @from as IEnumerable;
    if (objects != null)
        return objects.Cast<object>().ToArray();

    return new object[] { @from };
}