"Peter Duniho" <no.peted.spam@no.nwlink.spam.com> wrote in message
news:op.uwrzvezuvmc1hu@macbook-pro.local...
> On Wed, 08 Jul 2009 17:37:31 -0700, John A Grandy
> <johnagrandy-at-gmail-dot-com> wrote:
>
>> For :
>>
>> Dictionary<string,MyClass> myClasses;
>>
>> Is it possible to obtain a reference to object stored internally at the
>> lowest ordinal in the Dictionary , without using the key ?
>
> A Dictionary collection isn't ordered.  There's no element that can be
> considered "the lowest ordinal".
>
> That said, at any given moment you can of course enumerate the elements,
> and the first one might be considered "the lowest ordinal" at that
> moment.  But there's no guarantee it will remain the lowest ordinal after
> any kind of modification to the Dictionary.
>
> It's hard to tell from your examples what your actual requirement is,
> because you don't bother to state _why_ each example doesn't work.
>
>> [...]
>> If not possible to obtain reference to object stored at lowest ordinal in
>> Dictionary , is it possible to obtain a reference to *any* object stored
>> in
>> the dictionary ?  i.e. don't care what internal ordinal it's stored at.
>
> Of course.  You can always retrieve an arbitrary element within the
> Dictionary.  You can even retrieve the "first" element in the Dictionary
> at any moment, as long as you don't care whether that element is always
> going to be the first element.
>
> The examples you gave a pretty close to what you might try if you don't
> care about the element always being present in the same place in the
> collection (the first seemed entirely fine, and the second would have been
> fine if you didn't have a type mismatch), so without a clear statement as
> to why those examples aren't appropriate for your needs, it's not possible
> to suggest a proper alternative.
>
> Pete

"Peter Duniho" <no.peted.spam@no.nwlink.spam.com> wrote in message
news:op.uwr1gotovmc1hu@macbook-pro.local...
> On Wed, 08 Jul 2009 18:19:49 -0700, John A Grandy
> <johnagrandy-at-gmail-dot-com> wrote:
>
>> For,
>>
>> KeyValuePair<string,MyClass> kvp =
>> (KeyValuePair<string,MyClass>)myClasses[0];
>>
>> I get a compile error : invalid argument.
>
> How is "myClasses" declared?  If that's your Dictionary itself, no...it
> wouldn't.  You can only index by the key itself.  It would work if it was
> the result of converting your Dictionary via IEnumerable and then to, for
> example, a List<KeyValuePair<string, MyClass>>.
>
> Of course, a better approach might be just to do this:
>
>     KeyValuePair<string, MyClass> kvp = myClasses.First();
>
> Or even, depending on what data you actually want to retrieve:
>
>     MyClass element = myClasses.Values[0];
>
> But again, your question isn't very specific.  If you need the element
> returned to always be the same as the collection changes, that's not
> guaranteed to work.  If you just need any arbitrary element and the first
> one just happens to be handy, then either of the above ought to work.
>
> Pete

> For :
>
> Dictionary<string,MyClass> myClasses;
>
> Is it possible to obtain a reference to object stored internally at the
> lowest ordinal in the Dictionary , without using the key ?
>
> This does not work :
>
> KeyValuePair<string,MyClass> kvp =
> (KeyValuePair<string,MyClass>)myClasses[0];
> MyClass myClass0 = (MyClass)kvp.Value;
>
> Also, this does not work :
>
> KeyValuePair<string,MyClass> kvp =
> (KeyValuePair<string,MyClass>)myClasses.Values[0];
> MyClass myClass0 = (MyClass)kvp.Value;
>
>
> If not possible to obtain reference to object stored at lowest ordinal in
> Dictionary , is it possible to obtain a reference to *any* object stored in
> the dictionary ?  i.e. don't care what internal ordinal it's stored at.
>
>