Trying to get a linked list copy function working, my code is compiling hower it

Question

Trying to get a linked list copy function working, my code is compiling hower it is not copying when I test it. Can you review my code and suggest some changes or suggest an enitrely new code?

template <class T>

void ListType::copy(const ListType& otherList) {

   NodeType *newNode;
   NodeType *current;

   if (first != nullptr)
       destroy();
   if (otherList.first == nullptr)
   {
       first = nullptr;
       last = nullptr;
       count = 0;
   }
   else {
       current = otherList.first;
       count = otherList.count;
       first = new NodeType;
       first->info = current->info;
       first->link = nullptr;
           last = first;
       current = current->link;
       while (current != nullptr) {
           newNode = new NodeType;
           newNode->info = current->info;
           newNode->link = nullptr;
           last->link = newNode;
           last = newNode;
           current = current->link;
       }
   }
}

MAIN WHERE I AM TESTING IT:

#include
#include
#include "OListType.h"
#include "UListType.h"

using namespace std;

template
void testCopyConstructor(UListType);

int main()
{
   UListType list2;

for (int num = 0; num < 20; ++num)
       list2.insert(rand() % 100);
   cout << "List2: " << list2 << endl;
   cout << endl;

   testCopyConstructor(list2);
   cout << endl;

   UListType ulist2(list2);
   cout << ulist2 << endl;
   cout << endl;
   cout << "Testing Copy Constructor Complete if all three lists match." << endl;
   cout << endl;

   system("pause");
   return 0;
}
template
void testCopyConstructor(UListType otherList) {
   cout << otherList << endl;
}

Explanation / Answer

Hi Friend, Your 'copy' method is correct. But testing method is not correct .

You are not calling copy method anywhere.

I have modified main method and you can please let me know in case of any issue.

// THis is correct function
template <class T>
void ListType<T>::copy(const ListType& otherList) {
NodeType *newNode;
NodeType *current;
if (first != nullptr)
destroy();
if (otherList.first == nullptr)
{
first = nullptr;
last = nullptr;
count = 0;
}
else {
current = otherList.first;
count = otherList.count;
first = new NodeType;
first->info = current->info;
first->link = nullptr;
last = first;
current = current->link;
while (current != nullptr) {
newNode = new NodeType;
newNode->info = current->info;
newNode->link = nullptr;
last->link = newNode;
last = newNode;
current = current->link;
}
}
}

MAIN WHERE I AM TESTING IT:
#include <iostream>
#include <cstdlib>
#include "OListType.h"
#include "UListType.h"
using namespace std;
template
void testCopyConstructor(UListType);
int main()
{
UListType list2;
for (int num = 0; num < 20; ++num)
list2.insert(rand() % 100);
cout << "List2: " << list2 << endl;
cout << endl;
// THis method is not testing any copy construction.
// do not calling copy method anywhere
// testCopyConstructor(list2); // this is not class method
UListType copyList; // creating a new empty list
copyList.copy(list2); // copying the content if list2 in copyList
cout << copyList << endl; // printing the content of copyList
cout << endl;
UListType ulist2(list2);
cout << ulist2 << endl;
cout << endl;
cout << "Testing Copy Constructor Complete if all three lists match." << endl;
cout << endl;

system("pause");
return 0;
}

// here , how you are testing the copy construction
template
void testCopyConstructor(UListType otherList) {
cout << otherList << endl;
}

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