Initializing a hashtable?

I was adding data to the hashtable and i have to check for collision.
Well, in my strcmp its causing a crash since there is no data
and its not initialized.(i think) So, here i proceed to try to initialize it.
When i do it calls the operator= function where i dont know what to do with? whatever i try to do it just crashes. Probobly because s contains no data?

Here are my headers

Code:

---


class hashmap
{
public:
        hashmap(int capacity);
        ~hashmap(void);


        bool get(char const * const symbol, stock& s,
                int& symbolHash, int& hashIndex, int& usedIndex) const;


        bool put(const stock& s, int& symbolHash, int& hashIndex, int& usedIndex);

        bool remove(char const * const symbol, stock &s,
                int& symbolHash, int& hashIndex, int& usedIndex);

        friend ostream& operator<<(ostream& out, const hashmap& h);

private:

        stock* hashTable;                 
        size_t Tablesize;

        static int hashStr(char const * const symbol);        // hashing function

};

---

Code:

---


class stock
{
public:
        stock(char const * const symbol, char const * const name, int sharePrice, date priceDate);
        // sharePrice is given as a number of CENTS
        stock(const stock& s);                                                // copy constructor
        stock(void);                                                                // default constructor
        char const * const getSymbol(void) const;
        stock& operator=(const stock& s);
        stock& operator=(stock const * const s);
        ~stock(void);

        // display column headers
        static void displayHeaders(ostream& out);        // display the headers when this instance is printed

        // prints share price as DOLLARS
        // (e.g. 2483 would print out as 24.83 and 200 would print out as 2.00)
        friend ostream& operator<<(ostream& out, const stock& s);

        friend class hashmap;


private:

        int  sharePrice;
        char* name;
        char* symbol;
        date priceDate;
        int size;


};

---

This is where i am trying to initialize the table

Code:

---

hashmap::hashmap(int capacity): Tablesize(capacity),hashTable( new stock[capacity] )

{

for(int i=0; i<capacity; i++)
hashTable[i] = NULL;


}

---

then this function is callled:

Code:

---


stock& stock::operator=(stock const * const s)
{


        name = NULL;
        symbol = NULL;
        delete name;
        delete symbol;

        strcpy(name, s->name); // crashes


        return *this;
}

---

I think i need to do a copy here of some sort. however, what ever i do with s is crashes since s contains no data. What do i need to do in that function?

Why not check if 's' is NULL, and if it is return a NULL pointer without doing anything else, otherwise continue on with the overloading.

You shouldn't be assigning null to each object in the hashmap constructor. Either have the hashTable hold pointers to stock objects, or make sure that a default constructed stock object is valid.

Quote:

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Originally Posted by mrsirpoopsalot

Code:

---

stock& stock::operator=(stock const * const s)
{
        name = NULL;
        symbol = NULL;
        delete name;
        delete symbol;

        strcpy(name, s->name); // crashes

        return *this;
}

---

---

Are you sure you can't see a problem with executing even any two of these three statements in the order shown?:

Code:

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        name = NULL;
        delete name;
        strcpy(name, s->name);

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If this were building a house it would be roof, then walls, then foundations.