hash table explanation

Hi , do you guys know any good links or tutorials on hash tables since our proffessor didnt do a good job explaining that concept and I have this program to do

http://k4shif.netfirms.com/program4/prog4.html

thanks

>our proffessor didnt do a good job explaining that concept
A hash table is basically an array. That's not interesting except for the hash function. The hash function doles out numbers that match indexes of the array so that (ideally) each item you want to put into the array can only be hashed into a single unique index. In other words, this is a hash table:

Code:

---

int lettercount[27];

int hash(char c) { /* Assuming ASCII, deal */
        return c - 'a'; /* Lower case only */
}

int main ( ) {
        ...
        while ((ch = cin.get()) != EOF)
                lettercount[hash(ch)]++;
}

---

Each character from a to z is hashed to each array index from 0 to 26. That's what a hash table is, a way to take something that isn't an array index and make it into one so that you can access an array quickly and easily.