Hello,
in .net 2.0 I find
System.Collection.Specialized.OrderedDictionary.

Ok it's a dictionaly, collection of key-value-pairs and I have access over
index.

BUT:
Nothing about the kind of implementation.

So I have no idea, for what best to use this collection.

Is for example  myOrderedDictonary[myKey] fast or sequential slow?
Do I need hash for my keys or do I not?

So it's not possible to make good decicions to use this collection in the
right place.

Thank you for any help.

Hi Rolf,

As for the "OrderedDictionary" collection class you mentioned, it is a new
collection involved in .net framework 2.0.  Like a normal IDictionary based
collection, you can access entry in it through key e.g.

myOrderedDictionary[key]

or if you known a certain entry's ordered index, you can also use index to
locate the entry, e.g.

myOrderedDictionary[index]

Actually, both of the two access approach are quick and efficient because
OrderedDictionary has maintained two collection internally( one is a
hashTable and another is a ArrayList). Here is the disassembled code from
reflector:

=================
[Serializable]
public class OrderedDictionary : IOrderedDictionary, IDictionary,
ICollection, IEnumerable, ISerializable, IDeserializationCallback
{
....................
    private ArrayList _objectsArray;
    private Hashtable _objectsTable;
..............

public void Add(object key, object value)
{
    if (this._readOnly)
    {
        throw new
NotSupportedException(SR.GetString("OrderedDictionary_ReadOnly"));
    }
    this.objectsTable.Add(key, value);
    this.objectsArray.Add(new DictionaryEntry(key, value));
}
....................

==================

Therefore, whenever you add a new entry(key,value pair) into it, it will
add the entry's reference into both the internal hashtable and ArrayList.
Thus, it is efficient when you use either key or index to access items in
the OrderedDictionary.  You can also measure performance based on the
hashTable and ArrayList's item accessing.

Hope this helps.


Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead



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Hi Rolf,

Does the information in my last reply helps some? If you have any further
questions, please feel free to let me know.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


This posting is provided "AS IS" with no warranties, and confers no rights.

Hello,
thank you for your help.
It works fine.
Thank you again and best regards
Rolf Welskes


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