CODEWITHSUNDEEP
c++pointershash
Kaleb Meeks
Kaleb Meeks

Reputation: 111

"Error reading character of string" issue with growing array dynamically for hash (C++)

Everytime the code tries to insert the values from the old array into the new array in the grow function, I get an error "Error reading characters of string". I am trying to grow the array when it reaches a certain load factor. I have tried to figure out what the problem is but I don't know what it is. I have provide code for the grow, insert, and choosePrime function. The main problem is in the grow function, but I don't know if one of these other functions is affecting it.Any help is appreciated!

void grow() {
    int newCapacity = choosePrime();
    Slot **tmp = table;

    table = new Slot*[newCapacity];

    for (int i = 0; i < capacity; i++) {
        table[i] = NULL;
    }

    for (int i = 0; i < capacity; i++) {
        if (tmp[i] != NULL) {
            Insert(tmp[i]->key, tmp[i]->value);
            delete tmp[i];
        }
    }

    capacity = newCapacity;
    delete[] tmp;

}

/* Chooses Prime Number */

int choosePrime() {
    int n = capacity * 2;

    bool foundMultiple = false;

    do {
        n++;
        for (int i = 1; i < n; i++) {
            if (n % i == 0) {
                foundMultiple = true;
            }
        }
    } while(foundMultiple == false);

    return n;
}

bool Insert(string key, int value)
{
    if (float(size) / float(capacity) >= 0.5) {
        grow();
    }

    int h = hash(key);

    if (table[h] == NULL)
    {
        size++;
        table[h] = new Slot;
        table[h]->key = key;
        table[h]->value = value;
        table[h]->nextSlot = nullptr;

        return true;
    }
    else if (table[h]->key == key)
    {
        return false;
    }
    else
    {
        int p = probe(key, 1);

        for (int i = 1; h != p; p = probe(key, ++i))
        {
            if (table[p] == NULL)
            {
                size++;
                table[p] = new Slot;
                table[p]->key = key;
                table[p]->value = value;

                return true;
            }
            else if (table[p]->key == key)
            {
                return false;
            }
        }

        return false;
    }
}

Upvotes: 0

Views: 32

Answers (1)

1201ProgramAlarm
1201ProgramAlarm

Reputation: 32727

In grow, after allocating memory for a new table, you only set the original capacity elements to NULL. The "new" elements, from capacity to newCapacity are uninitialized.

Change your initialization loop to

for (int i = 0; i < newCapacity; i++)

Upvotes: 2

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