Though I am compiling all the cpp files and linking the object files I am getting the following error
g++ -c simple_list.cpp
g++ -c test_simple_list.cpp
g++ -o test_simple_list simple_list.o test_simple_list.o
/usr/bin/ld: test_simple_list.o: in function 'main':
test_simple_list.cpp:(.text+0x24): undefined reference to 'list<int>::list()'
/usr/bin/ld: test_simple_list.cpp:(.text+0x46): undefined reference to 'list<int>::push_front(int const&)'
/usr/bin/ld: test_simple_list.cpp:(.text+0x64): undefined reference to `std::ostream& operator<< (std::ostream&, list&)' /usr/bin/ld: test_simple_list.cpp:(.text+0x70): undefined reference to 'list::~list()' /usr/bin/ld: test_simple_list.cpp:(.text+0x99): undefined reference to 'list::~list()' collect2: error: ld returned 1 exit status
simple_list.h file
#ifndef __LIST__H__
#define __LIST__H__
#include <iostream>
#include <limits>
template < typename Elem >
struct Link {
Link * succ; // successor (next) link
Elem val; // the value
};
template < typename Elem >
class list {
private:
unsigned int lsize;
Link < Elem > * first;
Link < Elem > * last; // one beyond the last link
public:
class iterator;
list();
list & operator = (const list & obj);
bool empty();
unsigned int size();
iterator begin();
iterator end();
iterator insert_after(iterator p,
const Elem & v);
iterator erase_after(iterator p);
void push_front(const Elem & v);
Elem & front();
unsigned int max_size();
~list();
};
template < typename Elem >
std::ostream & operator << (std::ostream & os, list < Elem > & lt);
#endif
```
simple_list.cpp
```
#include "simple_list.h"
template < typename Elem >
class iterator {
private:
Link < Elem > * curr;
public:
iterator(Link < Elem > * curr) {
this -> curr = curr;
}
iterator & operator++() {
curr = curr -> succ;
return *this;
}
Elem & operator * () {
return curr -> value;
}
friend class list < Elem > ;
};
template < typename Elem >
list < Elem > ::list() {
first = last = new Link < Elem > ;
}
template < typename Elem >
list < Elem > & list < Elem > ::operator = (const list < Elem > & obj) {
typename list < Elem > ::iterator i = obj.begin();
typename list < Elem > ::iterator j = begin();
if (i == obj.begin()) {
push_front( * i);
}
while (i != obj.end()) {
i++;
insert_after(j, * i);
j++;
}
return *this;
}
template < typename Elem >
bool list < Elem > ::empty() {
if (size() == 0)
return false;
return true;
}
template < typename Elem >
unsigned int list < Elem > ::size() {
return size;
}
template < typename Elem >
typename list < Elem > ::iterator list < Elem > ::begin() {
return typename list < Elem > ::iterator(first);
}
template < typename Elem >
typename list < Elem > ::iterator list < Elem > ::end() {
return iterator(last);
}
template < typename Elem >
typename list < Elem > ::iterator list < Elem > ::erase_after(typename list < Elem > ::iterator p) {
Link < Elem > * curr = p.curr;
Link < Elem > * deleteLink = p.curr -> succ;
//Link<Elem> *deleteLinkSucc = deleteLink->succ;
p++;
if (p == end())
return end();
lsize--;
curr -> succ = p.curr;
return p;
}
template < typename Elem >
typename list < Elem > ::iterator list < Elem > ::insert_after(typename list < Elem > ::iterator p,
const Elem & v) {
Link < Elem > * newLink = new Link < Elem > ;
newLink -> val = v;
newLink -> succ = p.curr -> succ;
p.curr -> succ = newLink;
p++;
lsize++;
return p;
}
template < typename Elem >
void list < Elem > ::push_front(const Elem & v) {
Link < Elem > * newLink = new Link < Elem > ;
newLink -> val = v;
newLink -> succ = first;
first = newLink;
lsize++;
}
template < typename Elem >
Elem & list < Elem > ::front() {
return first -> val;
}
template < typename Elem >
unsigned int list < Elem > ::max_size() {
return std::numeric_limits < unsigned int > ::max();
}
template < typename Elem >
list < Elem > ::~list() {
while (first != last) {
Link < Elem > * temp = first -> succ;
delete first;
first = temp;
}
delete last;
}
template < typename Elem >
std::ostream & operator << (std::ostream & os, list < Elem > & lt) {
for (typename list < Elem > ::iterator i = lt.begin(); i != lt.end(); i++)
os << * i << " ";
return os;
}
```
test_simple_list.cpp file
```
#include "simple_list.h"
int main() {
list < int > a;
for (int i = 1; i <= 5; i++)
a.push_front(i);
std::cout << a;
}
```
