rehash help

Hi, working on this code, Im unsure about as to how to write the code for the rehashing, any hints pls??

Code:

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#ifndef _hashTable_h
#define _hashTable_h

#include <iostream>
#include <string>

using namespace std;

template<class KeyType, class DataType>
struct mypair
{  KeyType key;//words
    DataType data;//frequencies
};

template<class KeyType, class DataType>
class hashTable
{ 
public:
     
            hashTable(long int tSize = 0);//defined
        //Constructor function. Dynamically allocates the arrays, table
        //and status, with dimensions of the next prime number > tSize.
        //Initializes the status array to show all positions in the table
        //are empty and initializes size, tableSize, numSearches and
        //numProbes. Uses non-member function nextPrime.
       
        ~hashTable();//defined
       
       
    void find(const KeyType& k, long int& i, bool& found);
        //Looks for key, k, in table. If found then sets i to the subscript
        //where the key is located and sets found to true. If not found
        //then sets i to the subscript where the key could be inserted
        //and sets found to false. Uses linear probing for collision
        //resolution with inc determined from the hash value as follows:
        //i = hash(...); inc = i; if (inc == 0) inc = tableSize - 1 ; This 
        //is a little better than always taking inc = 1. Uses non-member
        //function hash.
 
    void insert(const KeyType& k, const DataType& d);
        //Inserts a pair with key k and data d into the table. If a pair
        //with the same key part already occurs in the table then it prints
        //an error message and does not insert the pair. If the table is
        //now more than 75% full then it rehashes into a larger table. Uses
        //the public member function find and the private member function
        //rehash.
       
 //************************************************************************
 //The following functions provide simialr capabilties to iterators in STL.
 //They allow one to examine all elements of the hash table. You could use
 //these for example to output all elements of the hash table or to copy all
 //elements to a vector outside the hashTable class for sorting, etc.
     
    const mypair<KeyType, DataType>& element(long int i) const;//defined
        //Returns the pair at subscript i in the table. Cannot be used
        //to assign a new value to the pair.
       
    DataType& data(long int i) const;//defined
        //Returns a reference to the data at subscript i in the table.
        //Can be used to assign a new value to the data.
       
    long int begin() const;//defined
        //Returns the subscript of the first element in the table; returns
        //the same value as end(), i.e. tableSize, if the table is empty.
       
    long int end() const;//defined
        //Returns subscript just past end of table, i.e. tableSize.
           
    long int next(long int i) const;//defined
        //Returns the subscript of the next element after i; if there is no
        //next element then returns the same as end(), i.e. tableSize.
       
       

//*************************************************************************
       
    float averageSearchLength() const;//defined
        //returns the average length of all searches numProbes/numSearches.
 
       
       
private:
    mypair<KeyType, DataType>* table; //dynamically allocated array of pairs
    short int* status;  //dynamically allocated status array; contains
                        //staus info: 0=empty, 1=occupied
    long int size; //number of elements in table
    long int tableSize; //size of table array
    long int numSearches; //total number of searches done in looking up keys.
                          //Increment numSearches each time find called.
    long int numProbes;  //total number of probes done during all searches.
                          //Increment each time find looks at a spot.
                                 
    void rehash();
        //The rehash function remembers the current table, status and tableSize
        //by assigning them to local variables, oldTable, oldStatus and
        //oldTableSize. It then dynamically allocates new table and status
        //arrays of size the next larger prime than oldTableSize and sets
        //tableSize to the new size. It then goes through the old table
        //and rehashes each element into the new table using the insert
        //function. Uses non-member function nextPrime.
};

template<class KeyType, class DataType>
const mypair<KeyType, DataType>&
hashTable<KeyType, DataType>::element(long int i) const
{  return table[i];
}
   
template<class KeyType, class DataType>
DataType& hashTable<KeyType, DataType>::data(long int i) const
{  return table[i].data;
} 

template<class KeyType, class DataType>
long int hashTable<KeyType, DataType>::begin() const
{  long int i = 0;

    while(i < tableSize && status[i] != 1)
        i++;
    return i;
}

template<class KeyType, class DataType>
long int hashTable<KeyType, DataType>::end() const
{  return tableSize;
}

template<class KeyType, class DataType>
long int hashTable<KeyType, DataType>::next(long int i) const
{ 
    i++;
    while(i < tableSize && status[i] != 1)
        i++;
    return i;
}

template<class KeyType, class DataType>
float hashTable<KeyType, DataType>::averageSearchLength()const
{
        return float(numProbes/numSearches);
}


template<class KeyType, class DataType>
hashTable<KeyType, DataType>::hashTable(long int tSize=0)
{
        tableSize=nextPrime(tSize);
        table = new mypair<KeyType, DataType>[tableSize];
        status=new short int [tableSize];
        for(int k=0;k<tableSize;k++)status[k]=0;
        size=0;
        numSeaches=0;
        numProbes=0;

}

template<class KeyType, class DataType>
hashTable<KeyType, DataType>::~hashTable()
{
        delete [] table;
        delete [] status;
}

template<class KeyType, class DataType>
void hashTable<KeyType, DataType>::insert(const KeyType& k, const DataType& d)
{
                        table[i].data=d;
                        table[i].key=k;
                        status[i]=1;
                        size++;
               
       

        if(size > .75*(tableSize))rehash();
}

template<class KeyType, class DataType>
void hashTable<KeyType, DataType>::find(const KeyType& k, long int& i, bool& found)
{
        i=hash(k);
        long int inc = i;

        if(inc == 0)inc = tableSize -1;

        while(status[i] != 1 && found == false)
        {
                if(table[inc].key==k)
                {
                        found=true;
                        i=inc;
                        table[inc].data++;
                }
                inc++;
                numProbes++;
                if(inc == tableSize)inc=0;
        }

        if(found == false)
        {
                long int k =i;

                while(status[k]!=0)
                {
                        k++;
                        numProbes++;
                        if(k==tableSize)k=0;
                }
                i=k;
        }
       
}

template<class KeyType, class DataType>
void hashTable<KeyType, DataType>::rehash()
{

}



 

//************************************************************************
//Non-member functions used in hashTable class.

    //This is the hash function to use for strings. If the KeyType is
    //anything other than string then this non-member function would
    //need to be changed to hash that type of key.
long int hash(string s, int tableSize)
{  int j;
    unsigned long int sum = 0;

    for (j = 0; j < s.length(); j++)
        sum = (sum << 5) + s[j];
       
    return sum % tableSize;
}

    //Returns the next prime >= n from a list of primes where
    //each is about twice as big as the previous one.
long int nextPrime(long int n)
{  long int i;
    long int p[18] = {      31,      61,    127,    251,    509,    1021,                       
                          2039,    4093,    8191,  16381,  32749,  65521, 
                        131071,  262139,  524287, 1048573, 2097143, 4194301
                    };

    for (i = 0; i < 18; i++)
      if (p[i] > n) return p[i];
     
    cerr<<"Next prime too large"<<endl;
    return p[17];
}

bool operator < (const mypair<string, int>& p,const mypair<string, int>& q)
{
        if(p.data < q.data)return true;

        else if ( p.data > q.data)return false;

        else
                return (p.key < q.key);
}



//************************************************************************
#endif

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i came up with this but cant figure out how to go further, any ideas??

Code:

---

template<class KeyType, class DataType>
void hashTable<KeyType, DataType>::rehash()
{
        //The rehash function remembers the current table, status and tableSize
    //by assigning them to local variables, oldTable, oldStatus and
    //oldTableSize

        mypair<KeyType, DataType> *oldTable=table;
        short int* oldStatus = status;
        long int oldTableSize = tableSize;

            //It then dynamically allocates new table and status
        //arrays of size the next larger prime than oldTableSize and sets
        //tableSize to the new size. It then goes through the old table
        //and rehashes each element into the new table using the insert
        //function. Uses non-member function nextPrime.

        table = new mypair<KeyType, DataType>[nextPrime(oldTableSize)]
        status = new short int[nextPrime(oldTableSize)];
        tableSize=nextPrime(oldTableSize);

        for(int i=0; i < oldTableSize;i++)
        {

        }

        delete[] oldTable;
        delete[] oldStatus;

       


}

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