Help with hash function

[chris11757]

The code for my hash function is below. I get an Unhandled excepation at .... Access violation reading location 0X00000001C.

long getHashValue(string City) {
		long sum = 0;
		long length = City.size();
		for (long i = 0; i < length; i++) {
			sum += (int)City[i];
		}
		sum *= 13;
		sum %= 1009;
		if (table[sum] != NULL) {
			while(table[sum]->getInfo().getCity() == City) {
				sum++;
			}
		}
		return sum;
	}

Here is the code for the whole program, note Information class just contains getter and setter methods.

#include <iostream>
#include <cstdlib>
#include <sstream>
#include <fstream>
#include "Information.h"
using namespace std;

class LinkedHashEntry {
private:
	int key;
	Information info;
	LinkedHashEntry *next;
public:
	LinkedHashEntry(int key, Information &info) {
		this->key = key;
		this->info.setCity(info.getCity());
		this->info.setState(info.getState());
		this->info.setLatitude(info.getLatitude());
		this->info.setLongitude(info.getLongitude());
		this->info.setPopulation(info.getPopulation());
		this->next = NULL;
	}

	int getKey() {
		return this->key;
	}

	Information getInfo() {
		return this->info;
	}

	void setInfo(Information &info) {
		this->info.setCity(info.getCity());
		this->info.setState(info.getState());
		this->info.setLatitude(info.getLatitude());
		this->info.setLongitude(info.getLongitude());
		this->info.setPopulation(info.getPopulation());
	}

	LinkedHashEntry *getNext() {
		return next;
	}

	void setNext(LinkedHashEntry *next) {
		this->next = next;
	}
};

const int TABLE_SIZE = 1009;

class HashMap {
private:
	float threshold;
	int maxSize;
	int tableSize;
	int size;
	int loadFactor;
	LinkedHashEntry **table;

	void resize() {
		int oldTableSize = tableSize;
		tableSize *= 2;
		maxSize = (int) (tableSize * threshold);
		LinkedHashEntry **oldTable = table;
		table = new LinkedHashEntry*[tableSize];
		for (int i = 0; i < tableSize; i++)
			table[i] = NULL;
		size = 0;
		for (int hash = 0; hash < oldTableSize; hash++) 
			if (oldTable[hash] != NULL) {
				LinkedHashEntry *oldEntry;
				LinkedHashEntry *entry = oldTable[hash];
				while (entry != NULL) {
					put(entry->getKey(), entry->getInfo());
					oldEntry = entry;
					entry = entry->getNext();
					delete oldEntry;
				}
			}
		delete[] oldTable;
	}

public: 
	HashMap() {
		threshold = 0.75f;
		maxSize = 96;
		tableSize = TABLE_SIZE;
		size = 0;
		table = new LinkedHashEntry*[tableSize];
		for (int i = 0; i < tableSize; i++)
			table[i] = NULL;
	}

	void setThreshold (float threshold) {
		this->threshold = threshold;
		maxSize = (int) (tableSize * threshold);
	}

	long getHashValue(string City) {
		long sum = 0;
		long length = City.size();
		for (long i = 0; i < length; i++) {
			sum += (int)City[i];
		}
		sum *= 13;
		sum %= 1009;
		if (table[sum] != NULL) {
			while(table[sum]->getInfo().getCity() == City) {
				sum++;
			}
		}
		return sum;
	}

	void get (long key, string City) {
		if (table[key] == NULL) {
			cout << City << " was not found!";
		}
		else {
			LinkedHashEntry *entry = table[key];
			for (entry; entry != NULL; entry=entry->getNext()) {
				Information info;
				info = entry->getInfo();
				cout << info.getCity() << ", " << info.getState() << ", " << info.getLatitude() << ", " << info.getLongitude() << ", " << info.getPopulation() << endl;
			}
		}
	}

	void put (long key, Information info) {
		if (table[key] == NULL) {
			table[key] = new LinkedHashEntry(key, info);
			size++;
		}
		else {
			LinkedHashEntry *entry = table[key];
			while (entry->getNext() != NULL)
				entry = entry->getNext();
			if (entry->getKey() == key)
				entry->setInfo(info);
			else
				entry->setNext(new LinkedHashEntry(key, info));
		}
		if (size >= maxSize)
			resize();
	}

	int getLoadFactor() {
		loadFactor = size / TABLE_SIZE;
		return loadFactor;
	}

	~HashMap() {
		for (int i = 0; i < TABLE_SIZE; i++)
			if (table[i] != NULL) {
				LinkedHashEntry *prevEntry = NULL;
				LinkedHashEntry *entry = table[i];
				while (entry != NULL) {
					prevEntry = entry;
					entry = entry->getNext();
					delete prevEntry;
				}
			}
		delete[] table;
	}
};

int main()
{
	ifstream inputFile;
	HashMap *map;
	map = new HashMap;
	long key;
	int loadFactor;
	double latitude, longitude, population;
	string inputFileName, line, city, state;
	string searchCity = "";
	Information *info;
	info = new Information;

	cout << "Please enter the name of the file: " ;
	cin >> inputFileName;

	inputFile.open(inputFileName.c_str());

	if(inputFile.good())
	{		
		cout << "File was opened!" << endl;
		while (inputFile.good())
		{
			getline(inputFile, line, '|');  //0
			getline(inputFile, line, '|');  //1 State
			info->setState(line);

			getline(inputFile, line, '|');  //2
			getline(inputFile, line, '|');  //3
			getline(inputFile, line, '|');  //4
			getline(inputFile, line, '|');  //5
			getline(inputFile, line, '|');  //6
			getline(inputFile, line, '|');  //7
			getline(inputFile, line, '|');  //8
			getline(inputFile, line, '|');  //9 Latitude
			latitude = ::atof(line.c_str());
			info->setLatitude(latitude);

			getline(inputFile, line, '|');  //10 Longitude
			longitude =::atof(line.c_str());
			info->setLongitude(longitude);

			getline(inputFile, line, '|');  //11
			getline(inputFile, line, '|');  //12
			getline(inputFile, line, '|');  //13
			getline(inputFile, line, '|');  //14	
			getline(inputFile, line, '|');  //15 
			getline(inputFile, line, '|');  //16 Population
			population =::atof(line.c_str());
			info->setPopulation(population);

			getline(inputFile, line, '|');  //17
			getline(inputFile, line, '\n');  //18 City
			info->setCity(line);

			key = map->getHashValue(info->getCity());
			map->put(key, *info);
			info = new Information;
		}

		loadFactor = map->getLoadFactor();
		cout << "The Load Factor of the table is: " << loadFactor << endl;
		cout << "Enter the name of the city you want to search or enter 0 to end the program." << endl;

		 while (searchCity != "0") {
			cout << "Enter the name of the city you want to search or enter 0 to end the program." << endl;
			getline(cin, searchCity);
			key = map->getHashValue(searchCity);
			map->get(key, searchCity);
		}
	}
	else {
		cout << "ERROR! Unable to open the specified file";
	}

	inputFile.close();
return EXIT_SUCCESS;
}

Thanks for your help I am just getting frustrated and it seems like everything I try gives me the unhandled exception message.

[chris11757]

Moving this to beginners forum so more people can see it.