C++ Display Function in a Class for Outputting Private Data to a CLL

[confundido]

I'm having some issues getting a class to output some information, when called from another class. I can't seem to figure out what is going wrong, and was hoping someone would be able to point out what is happening, or give me a push in the right direction.

The problem takes place in the queue::display function when I try to call the a_entry.display function. It returns garbage and I'm trying to figure out what is wrong with the entry::display function to make it not output correctly.

Let me know if you are able to assist.

Thank you.

Here is the code:

#include <cstring>
#include <cctype>
#include <iostream>

using namespace std;

class entry
{
  public:
    entry(void);
    ~entry(void);
    int create_entry(char*name, char*notes);
    void display(void);
    int copy_entry(const entry & copy_from);
    int retrieve(char * match, entry&found);

  private:
    char * name;
    char * notes;
};

entry::entry()
{

}

entry::~entry()
{
  //delete [] name;
  //delete [] notes;
}

struct q_Node
{
  entry a_entry;
  q_Node * next;
};

class queue
{
  public:
    queue(void);
    ~queue(void);
    int enqueue(const entry & to_add);
    int display();
    bool isEmpty();

  private:
    q_Node * rear;
    q_Node * front;
    int count;
};

queue::queue()
{
  front = rear = NULL;
  count = 0;
}

queue::~queue()
{
  rear->next = NULL;
  q_Node * temp;

  while(front)
  {
    temp=front->next;
    front->a_entry.~entry();
    delete front;
    front = temp;
  }
  rear = NULL;
}

int queue::enqueue(const entry & to_add) 
{ 
    if (front == NULL)
    { 
      cout << "Adding to front of queue." << endl;
      front = new q_Node;
      front->a_entry.copy_entry(to_add);
      rear = front;
      ++count;
      return 1;
    }

    else
    {
      cout << "Adding to the end of the queue." << endl;
      q_Node * temp = new q_Node;
      temp->a_entry.copy_entry(to_add);
      rear->next=temp;
      rear=temp;
      rear->next=front;
      ++count;
      return 1;
    }

    return 0; 
}

void entry::display()
{
  cout << "Route name: "<< name << endl;
  cout << "Route notes: " << notes << endl;
}

int queue::display() 
{ 
    q_Node *temp = front; 
    if (isEmpty())
      return 0;

    for(int i = 0; i < count; ++i)
    {
      temp->a_entry.display();
      temp = temp->next; 
    }

    return 1;
}

bool queue::isEmpty()
{
  if (count == 0)
    return 1;

  else
    return 0;
}

int entry::create_entry(char *name, char *notes)
{
  name = name;
  notes = notes;

  return 1;
}

int entry::copy_entry(const entry & copy_from)
{
  if (name)
    delete [] name;
  if (notes)
    delete [] notes;

  name = notes = NULL;

  if(copy_from.name)
  {
    name = new char[strlen(copy_from.name)+1];
    strcpy (name, copy_from.name);
  }
  else
    return 0;

  if (copy_from.notes)
  {
    notes = new char[strlen(copy_from.notes)+1];
    strcpy (notes, copy_from.notes);
  }
  else
    return 0;

  return 1;
}

int entry::retrieve(char*match, entry&found)
{
  if (!name || !match)
    return 0;

  if (!strcmp(name, match))
  {
    if(found.name)
      delete [] found.name;
    if(found.notes)
      delete [] found.notes;
    found.name=found.notes=NULL;

    found.name = new char[strlen(name)+1];
    strcpy(found.name, name);

    found.notes = new char[strlen(notes)+1];
    strcpy(found.notes, notes);

    return 1;
  }

  return 0;
}

int main()
{

  char name[100], notes[100];
  entry to_add;
  queue my_route;

  cout << "Enter route name:" << endl;
  cin.get(name, 100); cin.ignore(100,'\n');
  cout << "Enter route notes:" << endl;
  cin.get(notes, 100); cin.ignore(100,'\n');
  to_add.create_entry(name, notes);
  my_route.enqueue(to_add);

  cout << "Enter route name:" << endl;
  cin.get(name, 100); cin.ignore(100,'\n');
  cout << "Enter route notes:" << endl;
  cin.get(notes, 100); cin.ignore(100,'\n');
  to_add.create_entry(name, notes);
  my_route.enqueue(to_add);

  my_route.display();

  cout << "END" << endl;
  

  return 0;

}

Here's the input/output:

Enter route name:
test
Enter route notes:
test
Adding to front of queue.
Enter route name:
test
Enter route notes:
test
Adding to the end of the queue.
Route name: �v�
Route notes: H�
Route name: �v�
Route notes: H�

[dutch]

On lines 134 and 135 above, you are doing this:

  name = name;
  notes = notes;

That assigns the variables to themselves! You want to assign them to your class members, like so:

  this->name = name;
  this->notes = notes;

Your compiler should've warned you about that. Don't ignore compiler warnings. If it didn't emit a warning, then turn up the warning level to maximum. E.g., with g++ or clang++ you add the flags -Wall -W -pedantic.