Linked List Code for Beginners

#include "stdafx.h"
#include <iostream>

#ifndef _DSCLASS_H_
#define _DSCLASS_H_
class linkedlist{
private:
    struct node{
        int data;
        node *link;
    }*list;
public:
    linkedlist();
    ~linkedlist();
    //stack methods
    void push_item(int num);
    void pop_item();

    //queue methods
    void append_item(int num);
    void delete_item();

    //other insertion and deletion methods
    void insert_item(int pos,int num);
    void delete_item(int pos);

    //other operations
    void reverse();
    void merge(linkedlist l1, linkedlist l2);
    linkedlist operator +(linkedlist l1);

    void display();
};
linkedlist::linkedlist()
{
    list = NULL;
}
linkedlist::~linkedlist()
{
    //TODO: yet to be implemented
}

void linkedlist::insert_item(int pos, int num)
{
    
    if (pos<0)    return;
    printf("inserting %d at %dth position...\n", num, pos);
    
    node *newone;
    node *ptr = list;
    
    if (pos==0) 
    {
    newone    = new node();
    newone->data = num;
    newone->link = ptr;
    list = newone;
    return;
    }

    for (int i=0;i<pos-1;i++)
    {    
        if (ptr!=NULL) ptr=ptr->link;
        else return;
    }

    newone    = new node();
    newone->data = num;
        
    if(ptr->link!=NULL) newone->link = ptr->link;
    else newone->link = NULL;
    
    ptr->link =newone;


}

void linkedlist::delete_item(int pos)
{
if (list == NULL && pos<0) return;
printf("deleting item at %d position...\n",pos);
if (pos==0)//deleting the head
{
    node *temp = list;
    list = list->link;
    delete temp;
    return;
}

node *ptr = list;
node *temp;
for (int i=0;i<pos-1;i++)
{
    if (ptr!=NULL)
    {
        temp = ptr;
        ptr = ptr->link;
    }
    else return;
}

if (ptr->link!=NULL)
    temp->link = ptr->link;
else
    temp->link = NULL;

delete ptr;

}

void linkedlist::push_item(int num)
{
    printf("pushing %d..\n",num);
    if (list == NULL)
    {
        list = new node();
        list->data = num;
        list->link = NULL;
    }
    else
    {
        node* t = new node();
        t->data = num;
        t->link = list;
        list =t;
    }

}

void linkedlist::append_item(int num)
{
 printf("appending %d..\n",num);
 if (list == NULL)
 {
     list = new node();
     list->data = num;
     list->link = NULL;
 }
 else
 {
     node* par = list;
     while (par->link != NULL)
     {
        par=par->link;
     }
     //now we are at the end
     node *newone = new node();
     newone->data = num;
     newone->link = NULL;
     par->link = newone;
 }
}


void linkedlist::pop_item()
{
    printf("popping ..\n");
    if (list ==NULL)
    {
        printf("empty list\n");
        return;
    }
    else
    {
        node *del = list;
        list = list->link;
        delete del;
    }
}


void linkedlist::delete_item()
{
    printf("deleting ..\n");
    if (list==NULL)
    {
        printf("empty list\n");
        return;
    }
    else
    {
        node *del = list;
        node *temp = NULL;
        while(del->link!=NULL)
        {
            temp = del;
            del = del->link;
        }
        if (temp!=NULL) temp->link = NULL;
        delete del;
        if(del==list) list = NULL;
        
    }
}
void linkedlist::display()
{
    if (list==NULL)
        return;

    node *dis = list;
    char str[100]="";
    while (dis!=NULL)
    {
     sprintf(str,"%s%d->",str,dis->data);
     dis=dis->link;
    }
    printf("%sNULL\n",str);
}

void linkedlist::reverse()
{
    printf("reversing...");
    if (list == NULL && list->link == NULL) return;
    node *current = list;
    node *prev = NULL;
    node *next = NULL;
    while (current!=NULL)
    {
        next = current->link;
        current->link = prev;
        prev= current;
        current = next;
    }
    list = prev;

}

void linkedlist::merge(linkedlist l1, linkedlist l2)
{

    node *top = l1.list;
    while (top!=NULL)
    {
        append_item(top->data);
        top = top->link;
    }
    top = l2.list;
    while (top!=NULL)
    {
        append_item(top->data);
        top = top->link;
    }
    
}

linkedlist linkedlist:: operator +(linkedlist l1)
{
    linkedlist temp;

    node *top = this->list;
    while (top!=NULL)
    {
        temp.append_item(top->data);
        top = top->link;
    }

    top = l1.list;
    while (top!=NULL)
    {
        temp.append_item(top->data);
        top = top->link;
    }
return temp;
}
#endif