C++ Hash Table using chaining, remove method - c++

Question

I'm implementing a Hash Table in C++ using chaining. The code builds with no errors and the table constucts fine using the insert method. However, when I call the remove method I receive the following error:
Unhandled exception at 0x00c53be9 in HashTable.exe: 0xC0000005: Access violation reading location 0x00000000.
Hash Entry Code:
#include <string>
#include <vector>
template <class T>
class HashEntry
{
private:
int key; //lookup key
T value; //hash data
HashEntry<T> *next;
public:
HashEntry(int key, T value);
HashEntry();
int& getKey();
T& getValue();
void setValue(T value);
HashEntry<T>* getNext();
void setNext(HashEntry *next);
bool operator == (HashEntry& rhs);
bool operator != (HashEntry& rhs);
HashEntry<T>& operator = (HashEntry& rhs);
};
template <class T>
HashEntry<T>::HashEntry(int key, T value)
{
this->key = key;
this->value = value;
this->next= nullptr;
}
template <class T>
HashEntry<T>::HashEntry()
{
this->key = 0;
this->next= nullptr;
}
template <class T>
int& HashEntry<T>::getKey()
{
return key;
}
template <class T>
T& HashEntry<T>::getValue()
{
return value;
}
template <class T>
void HashEntry<T>::setValue(T value)
{
this->value = value;
}
template <class T>
HashEntry<T>* HashEntry<T>::getNext()
{
return next;
}
template <class T>
void HashEntry<T>::setNext (HashEntry *next)
{
this->next = next;
}
template <class T>
bool HashEntry<T>::operator == (HashEntry& rhs)
{
return ((this->getKey() == rhs.getKey()) && (this->getValue() == rhs.getValue()));
}
template <class T>
bool HashEntry<T>::operator != (HashEntry& rhs)
{
return ((this->getKey() != rhs.getKey()) && (this->getValue() != rhs.getValue()));
}
template <class T>
HashEntry<T>& HashEntry<T>::operator = (HashEntry& rhs)
{
this->key = rhs.getKey();
this->value = rhs.getValue();
this->next = rhs.getNext();
return *this;
}
Hash Table code:
template <class T>
class HashTable
{
private:
std::vector<HashEntry<T>> table;
static const int DEFAULT_TABLE_SIZE = 128;
int TABLE_SIZE;
public:
HashTable();
void insert(int key, T value);
void remove(int key);
void get(int key);
~HashTable();
};
template <class T>
HashTable<T>::HashTable()
{
TABLE_SIZE = DEFAULT_TABLE_SIZE;
table.resize(TABLE_SIZE);
}
Remove Method Code:
template <class T>
void HashTable<T>::remove(int key)
{
int hashFunc = (key % TABLE_SIZE);
if (table[hashFunc] != HashEntry<T>())
{
HashEntry<T> prevEntry = HashEntry<T>();
HashEntry<T> entry = table[hashFunc];
while (entry.getNext() != nullptr && entry.getKey() != key)
{
prevEntry = entry;
entry = *entry.getNext();
}
if (entry.getKey() == key)
{
if (prevEntry == HashEntry<T>())
{
HashEntry<T> nextEntry = *entry.getNext(); //Where the exception is thrown
entry = HashEntry<T>();
table[hashFunc] = nextEntry;
}
else
{
HashEntry<T> *next = entry.getNext();
entry = HashEntry<T>();
prevEntry.setNext(next);
}
}
}
}

Answer 1

while (entry.getNext() != nullptr && entry.getKey() != key)
{
prevEntry = entry;
entry = *entry.getNext();
}
Few lines later, using entry generated above:
HashEntry<T> nextEntry = *entry.getNext(); //Where the exception is thrown
The while "makes" entry.getNext() a nullptr. And, later, you are trying to dereference it. And dereferencing nullptr... is a Bad Thing (tm).
Btw., why aren't you operating on pointers? I may be wrong, but looking at your code, I have a feeling that you want to modify original objects... and local objects looks like copies.