copy n k/v pairs from Hashtable

Question

I have a hashtable with n number of records. I need to copy out the records between x and y and iterate through them.

How would I do this?

Example:

HT1.Count = 500;

HT2 = HT1[0] - HT1[100];

--edit--

Just so you are aware, the reasoning for this is I am generating PDF's from .MSG files. The problem arises for the end user that when they get a 12GB PDF it causes issues :P

I need to break the PDF's into messages of 250, and then start a new PDF. So order does not really matter, neither does returning the same records each time, as it will only be done once.

Answer 1

My bet would be doing a custom function like this:

public IEnumerable<object> GetRange(Hashtable ht, int min, int max) {
    int i = 0;
    foreach (var key in ht.Keys) {
        i++;
        if (i > max) {
            yield break;
        }
        if (i >= min) {
            yield return ht[key];
        } else continue;
    }
}

However, take into account that the order of the keys is not guaranteed, so this can have an unordered sequence of objects

Answer 2

As others have stated, you cannot iterate over a hashtable in the way you seem to want. If, on the other hand, what you want is the result where the keys are in that range, you can do something like this:

    public IDictionary<int, T> GetRange<T>(
        IDictionary<int, T> source, int min, int max)
    {
        // add error checking for min,max, null, etc...
        int capacity = Math.Max(0, max - min);
        Dictionary<int, T> target = new Dictionary<int, T>(capacity);
        for (int key = min; key < max; key++)
        {
            if (source.ContainsKey(key))
            {
                target.Add(key, source[key]);
            }
        }
        return target;
    }

Note that I am using the generic version (Dictionary) instead of the old Hashtable, but the idea would be the same.

Answer 3

I suggest you consult a reference on hash tables. Hash tables are generally unordered, so your question is meaningless.