class Dictionary in c#

madsiro · #1 20-Apr-2008, 14:02

Hi, I'm programming in C #, and I have a question about the class dictionary, I know that this work as a hash table, but I would like to know how that hash function uses (or which is the one that could use), and that size is its table, here is an example of Dictionary, and here is my question.

C-SHARP / C# Code:

private static Dictionary<string, double> PrepareFrequency(string[] words)
{
    Dictionary<string, double> table = new Dictionary<string, double>();

    foreach (string word in words)
    {
        if (table.ContainsKey(word))
            table[word]++;
        else
            table.Add(word, 1);
    }

    return table;
}

Thanks for your attention.

LuciWiz · #2 21-Apr-2008, 07:01

Quote:

Originally Posted by madsiro

[snip]and here is my question.

What is the question?

madsiro · #3 21-Apr-2008, 11:09

Quote:

Originally Posted by LuciWiz

What is the question?

Thanks for your replay, my question is
What function dispersion could be using Dictionary?

Menol_LK · #4 23-Jun-2008, 01:40

Dictionary is an extended version of Hash Table when it comes to .Net.

there are differences between .net hash table and dictionary,

some of them are:

* dictionary maintains the order that you add items to it where as hash table (in .net) does not

* Hash table allows you to avoid providing a key when you add an item by using a null value as key but a dictionary will raise an exception if you don't provide a key.
* etc.

basically, what a hash function does is it derives a small number from a large amount of data in a way that you can use that number to uniquely identify that particular data. Or in other words, you can use that number as an index to search among data.

According to my knowledge, Hashing is a theory that comes under Database Management (Not with programming) so if you want to learn more about hash
functions you should dig in data base area rather than programming sites.

I suggest you to go and read following wiki page :

http://en.wikipedia.org/wiki/Hash_function

Menol
menol.blogspot.com

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class Dictionary in c#

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