I have created a custom map for an assignment (It’s a generic templated map with it’s own custom iterator and a partial specialisation) but I’m getting undefined references to all of it’s functions when the application tries to use it in it’s code.
I have loooked at other questions on here with similar circumstances and I’m guessing I’ve got a mistake in my namespace or the location of the iterator or something that’s causing the application to not find it?
Here’s the relevant code:
#ifndef MAP_H
#define MAP_H
#define SIZE 101
#include <string>
using std::string;
namespace myMap{
////////////////////START TEMPLATE//////////////////////
template<class K, class V>
class map
{
private:
typedef struct SNode{
K first;
V second;
SNode* next;
} Node;
Node** hashArray;
Node* head;
Node* tail;
Node* lastEntry;
public:
map();
~map();
V generateHash(K first);
void addPair(K first, V second);
void checkHeadTail();
int count(K key);
V& operator[](K first);
class iterator
{
private:
Node* currentNode;
K first;
V second;
public:
iterator();
iterator(Node* pos);
~iterator();
void operator++(int);
Node* operator->();
bool operator!=(iterator other);
};
iterator begin(){iterator iter(head); return iter;}
iterator end(){iterator iter(NULL); return iter;}
};
template<class K, class V>
map<K, V>::map()
{
hashArray = new Node*[SIZE];
for(unsigned int i = 0; i < SIZE; i++){
hashArray[i] = NULL;
}
head = NULL;
tail = NULL;
lastEntry = NULL;
}
template<class K, class V>
map<K, V>::~map()
{
for(unsigned int i = 0; i < SIZE; i++){
if(hashArray[i] != NULL){
Node* tmpNode = hashArray[i];
Node* currentNode = hashArray[i];
while(currentNode){
currentNode = currentNode->next;
delete tmpNode;
tmpNode = currentNode;
}
}
}
delete [] hashArray;
}
template<class K, class V>
V map<K, V>::generateHash(K first)
{
V hash = 0;
for(unsigned int j = 0; j < first.length(); j++){
hash += first[j];
}
return hash % SIZE;
}
template<class K, class V>
void map<K, V>::checkHeadTail()
{
if(hashArray[0] != NULL){
head = hashArray[0];
tail = hashArray[0];
}
Node* currentNode = *hashArray;
while(currentNode->next){
currentNode = currentNode->next;
}
tail = currentNode;
}
template<class K, class V>
void map<K, V>::addPair(K first, V second)
{
Node* newEntry = new Node;
newEntry->first = first;
newEntry->second = second;
newEntry->next = NULL;
V hash = generateHash(first);
if(hashArray[hash] == NULL){
hashArray[hash] = newEntry;
lastEntry = newEntry;
} else {
Node* currentNode = hashArray[hash];
while(currentNode->next){
if(currentNode->first == first){
currentNode->second += second;
lastEntry = currentNode;
return;
}
currentNode = currentNode->next;
}
if(currentNode->first == first){
currentNode->second += second;
lastEntry = currentNode;
return;
} else {
currentNode->next = newEntry;
lastEntry = newEntry;
return;
}
}
checkHeadTail();
}
template<class K, class V>
V& map<K, V>::operator[](K first)
{
V second = 0;
addPair(first, second);
return lastEntry->second;
checkHeadTail();
}
template<class K, class V>
int map<K, V>::count(K key)
{
V hash = generateHash(key);
if(hashArray[hash] != NULL){
return true;
}
return false;
}
template<class K, class V>
void map<K, V>::iterator::operator++(int)
{
currentNode = currentNode->next;
}
template<class K, class V>
bool map<K, V>::iterator::operator!=(map::iterator other)
{
if(first == other->first) return false; return true;
}
template<class K, class V>
typename map<K, V>::Node* map<K, V>::iterator::operator->()
{
return currentNode;
}
template<class K, class V>
map<K, V>::iterator::iterator()
{
currentNode = NULL;
}
template<class K, class V>
map<K, V>::iterator::iterator(Node* pos)
{
currentNode = pos;
}
////////////////////SPECIALISATION///////////////////////////////
template<class V>
class map<string, V>
{
private:
typedef struct SNode{
string first;
V second;
SNode* next;
} Node;
Node** hashArray;
Node* head;
Node* tail;
Node* lastEntry;
public:
map();
~map();
V generateHash(string first);
void addPair(string first, V second);
void checkHeadTail();
V count(string key);
V& operator[](string first);
class iterator
{
private:
Node* currentNode;
string first;
V second;
public:
iterator();
iterator(Node* pos);
~iterator();
void operator++(V);
Node* operator->();
bool operator!=(iterator other);
};
iterator begin();
iterator end();
};
template<class V>
map<string, V>::map()
{
hashArray = new Node*[SIZE];
for(unsigned int i = 0; i < SIZE; i++){
hashArray[i] = NULL;
}
head = NULL;
tail = NULL;
lastEntry = NULL;
}
template<class V>
map<string, V>::~map()
{
for(unsigned int i = 0; i < SIZE; i++){
if(hashArray[i] != NULL){
Node* tmpNode = hashArray[i];
Node* currentNode = hashArray[i];
while(currentNode){
currentNode = currentNode->next;
delete tmpNode;
tmpNode = currentNode;
}
}
}
delete [] hashArray;
}
template<class V>
V map<string, V>::generateHash(string first)
{
unsigned long hash = 0;
for(unsigned int j = 0; j < first.length(); j++){
hash += first[j];
}
return (V) hash % SIZE;
}
template<class V>
void map<string, V>::checkHeadTail()
{
if(hashArray[0] != NULL){
head = hashArray[0];
tail = hashArray[0];
}
Node* currentNode = *hashArray;
while(currentNode->next){
currentNode = currentNode->next;
}
tail = currentNode;
}
template<class V>
void map<string, V>::addPair(string first, V second)
{
Node* newEntry = new Node;
newEntry->first = first;
newEntry->second = second;
newEntry->next = NULL;
V hash = generateHash(first);
if(hashArray[hash] == NULL){
hashArray[hash] = newEntry;
lastEntry = newEntry;
} else {
Node* currentNode = hashArray[hash];
while(currentNode->next){
if(currentNode->first == first){
currentNode->second += second;
lastEntry = currentNode;
return;
}
currentNode = currentNode->next;
}
if(currentNode->first == first){
currentNode->second += second;
lastEntry = currentNode;
return;
} else {
currentNode->next = newEntry;
lastEntry = newEntry;
return;
}
}
checkHeadTail();
}
template<class V>
V& map<string, V>::operator[](string first)
{
V second = 0;
addPair(first, second);
return lastEntry->second;
checkHeadTail();
}
template<class V>
V map<string, V>::count(string key)
{
V hash = generateHash(key);
if(hashArray[hash] != NULL){
return true;
}
return false;
}
template<class V>
map<string, V>::iterator::iterator()
{
currentNode = NULL;
}
template<class V>
map<string, V>::iterator::iterator(Node* pos)
{
currentNode = pos;
}
template<class V>
void map<string,V>::iterator::operator++(V)
{
currentNode = currentNode->next;
}
template<class V>
typename map<string, V>::Node* map<string, V>::iterator::operator->()
{
return currentNode;
}
template<class V>
bool map<string, V>::iterator::operator!=(map::iterator other)
{
if(first == other->first) return false; return true;
}
} // END NAMESPACE
#endif // MAP_H
Errors:
undefined reference to `myMap::map<std::string, int>::begin()'
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::end()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::begin()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::end()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
undefined reference to `myMap::map<std::string, int>::iterator::~iterator()'|
Erros occur when application tries to use the iterator as so:
map<string, int>::iterator iter;
for(iter = wordsCount.begin(); iter != wordsCount.end(); iter++){
orderedList.addWord(iter->first, iter->second);
}
As part of the assignment, I am not allowed to change the use of the iterator above only the implementation, which I have had to create myself.
The implementation for the member functions which cause the error message are not in the header file for
map<string, V>. I don’t see the implementations ofmap::begin(),map::end()andmap::iterator::~iterator()anywhere. The most other functions seem to be implemented (didn’t check all), but those three are missing.map<K, V>implementsbegin()andend()inside the class, but the implementation ofiterator::~iterator()is missing there, too.