Open address hashtable segmentation fault - c++

Question

Iam trying to create an open addressed hash table. The user has to be able to define the table's size. For my collision resolution I am using psuedo random probing -
http://algoviz.org/OpenDSA/Books/OpenDSA/html/HashCImproved.html#HashingPseudoRandomProbePRO
Anyway the hashing function(s) seem to work fine until I only have 1 more space to fill in the table. As soon as I input the final element of the table my program crashes and I get a segmentation fault. I've been pulling my hair out trying to find the problem for hours. Please help!
#include <iostream>
#include <string>
#include <sstream>
#include <algorithm>
#include <vector>
using namespace std;
class HashTable
{
string* hash;
bool* inTable;
vector<int> perm;
int table_size;
int permFunc(int, int);
void permutation();
int hashFunc(string);
public:
//constructor for a hashtable
HashTable(int);
//deconstructor for hashtable
~HashTable();
bool isFull();
//The prototype for the insert method
void insert(string);
//The prototype for the lookup method
bool lookup(string);
//The prototype for the remove method
void remove(string);
//The prototype for the size method
int size();
//The prototype for the print method
void print();
};
//constructor
HashTable::HashTable(int table_size)
{
this -> table_size = table_size;
hash = new string[table_size];
inTable = new bool[table_size];
for(int i=0; i<table_size; i++) perm.push_back(i);
permutation();
}
//deconstructor
HashTable::~HashTable()
{
delete [] hash;
delete [] inTable;
}
//creates a permutation of the perm vectors index elements
void HashTable::permutation()
{
random_shuffle ( perm.begin() + 1, perm.end() );
}
//Hash function method for strings
int HashTable::hashFunc(string str)
{
int key = 0;
for (int i=0; i < str.size(); i++)
{
key += static_cast<int>(str.at(i));
}
cout << "key is:" << key << endl;
return key%table_size;
}
int HashTable::permFunc(int index, int i)
{
int temp = index;
index += perm[i];
if(index > table_size){index = index - table_size;}
if(inTable[index] == false ){return index;}
index = temp;
i++;
permFunc(index, i);
}
bool HashTable::isFull()
{
int num=0;
for(int i=0;i<table_size; i++)
{
if(inTable[i] == true){num ++;}
if(num == table_size){
cout<<"FULL TABLE";
return true;}
}
return false;
}
//Method that inserts an integer into the hash table
void HashTable::insert(string str)
{
int i=1;
if(isFull()){return;}
int pos = hashFunc(str);
if(inTable[pos] == true)
{
int permPos = permFunc(pos, i);
hash[permPos] = str;
inTable[permPos] = true;
}
else
hash[pos] = str;
inTable[pos] = true;
}
//A function that prints out the menu
void menu()
{
cout << endl;
cout << "press i to insert an element into the hash table" << endl;
cout << "press d to inTableete an element from the hash table" << endl;
cout << "press l to look up an element" << endl;
cout << "press s to obtain the size of the table" << endl;
cout << "press p to print the current table" << endl;
return;
}
//The main method
//Implements all the input and output
int main(void)
{
int table_size;
cout << "Enter table size: ";
cin >> table_size;
HashTable h(table_size);
while(true)
{
char c;
string str;
menu();
getline(cin, str);
stringstream stream;
stream << str;
stream >> c;
switch(c)
{
case 'i':
getline(cin, str);
h.insert(str);
break;
case 'd':
getline(cin, str);
h.remove(str);
break;
case 'l':
getline(cin, str);
cout << h.lookup(str) << "\n";
break;
case 's':
cout << h.size() << "\n";
break;
case 'p':
h.print();
break;
default:
cout << "Don't understand '" << c << "'\n";
}
}
return 0;
}

Answer 1

I don't know if this is your problem but this line:
if(index > table_size){index = index - table_size;}
will leave index at table_size which is out of bounds for your array. Change the > to >=
If this isn't it, could you add an example crashing input to your post, for testing?