Ques-4.cpp

/*
QUESTION-4:
            Implement Doubly Linked List using templates. Include functions for insertion, deletion and
            search of a number, reverse the list.
SOLUTION:
*/
#include<iostream>
using namespace std;
template<class t>
class node
{
public:
t data;
node *prev,*next;
};
template<class t>
class dlist
{
int n;
node<t> *first,*last;
public:
dlist()
{
first=NULL;
last=NULL;
}
//create function
void create()
{
node<t> *current,*temp;
char ch;
//fflush(stdin);
first=new node<t>;
cout<<"Enter data for first node:\n";
cin>>first->data;
current=first;
first->next=NULL;
first->prev=NULL;
last=first;
do
{
cout<<"Want to enter more data(y/n):\n";
cin>>ch;
if(ch=='y')
{
n=count();
this->insert(n+1); }
}while(ch=='y');
}
//display function
void display()
{
node<t> *current;
current=first;
cout<<"The data in linked list:\n";
while(current!=NULL)
{
cout<<current->data<<" <-> ";
current=current->next;
}
cout<<"\n";
}
//reverse function
void reverse()
{
n=count();
//fflush(stdin);
node<t> *current;
current=last;
cout<<"The data after reversing the linked list:\n";
for(int i=1;i<=n;i++)
{
cout<<current->data<<" -> ";
current=current->prev;
}
}
//count function
int count()
{
int c=0;
node<t> *current;
current=first;
while(current!=NULL)
{
c++;
current=current->next;
}
return c;
}
//insert function
void insert(int n1)
{
int b=count();
if(n1<=b+1)
{
node<t> *current,*forward,*temp;
current=first;
temp=new node<t>;
cout<<"Enter data:\n";
cin>>temp->data;
temp->next=temp->prev=NULL;
if(n1==1)
{
temp->next=first;
first->prev=temp;
first=temp;
}
else if(n1<=b)
{
for(int i=1;i<n-1;i++)
current=current->next;
forward=current->next;
temp->next=forward;
current->next=temp;
temp->prev=current;
forward->prev=temp;
}
else
{
last->next=temp;
temp->prev=last;
last=temp;
}
}
else
cout<<"Can't be inserted\n";
}
//search function
void search()
{
int flag=0;
cout<<"Enter data to be searched:\n";
cin>>n;
node<t> *current,*previ,*temp;
int b=count();
current=first;
for(int i=1;i<=b;i++)
{
if(current->data==n)
{
flag=1;
break;
}
current=current->next;
}
if(flag!=0)
{
previ=current->prev;
int c;
cout<<"Data found:\nEnter what you want do:\n 1.delete data\n 2.replace it\n 3.do nothing\n";
cin>>c;
switch(c)
{
case
1:temp=current;
if(current->next!=NULL)
{
current=current->next;
previ->next=current;
current->prev=previ;
}
else
{
previ->next=NULL;
current->prev=NULL;
}
delete(temp);
cout<<"Data deleted:\n";
this->display();
break;
case
2:cout<<"Enter new data:\n";
cin>>current->data;
cout<<"data replaced:\n";
this->display();
break;
case 3:break;
default:cout<<"wrong choice:\n";
}
//getchar();
}
else
cout<<"Data not found:\n";
}
//overloading + operator
dlist operator +(dlist l)
{
dlist l6;
l6.first=first;
l6.last=last;
l6.last->next=l.first;
l.first->prev=l6.last;
return l6;
}
};
int main()
{

int choice,n;
char ch;
dlist<int> l1,l3,l2;
l1.create();
l1.display();
do
    {
        cout<<"\n********Which operation you want to perform in Doubly Linked List ***********";
        cout<<"\n1. Insert element(INSERTION).";
        cout<<"\n2. Deletion .";
        cout<<"\n3. Search an element.";
        cout<<"\n4. Reversing an element.";
        cout<<"\n5. Exit.";
        cout<<"\nEnter your choice: ";
        cin>>choice;
        
        switch(choice)
        {
            case 1: 
                    //doing insertion
                    do
                    {
                    cout<<"Want to insert a node(y/n):\n";
                    cin>>ch;
                    if(ch=='y')
                    {
                    cout<<"Enter the position of insertion;\n";
                    cin>>n;
                    l1.insert(n);
                    }
                    }while(ch=='y');
                    cout<<"The linked list after all insertions:\n";
                    l1.display();
                    
            case 2: cout<<"\nValue to be deleted from List. ";
                    cin>>n;
                    cout<<"Data deleted:\n";
                    break;
                    break;
                    
            case 3: 
                    cout<<"search Element\n";
                        do
                        {
                        cout<<"Want to search a data(y/n):\n";
                        cin>>ch;
                        if(ch=='y')
                        l1.search();
                        }while(ch=='y');
                        cout<<"The linked list after searching and as so:\n";
                        l1.display();
                        break;
        
                    
            case 4: 
                    cout<<"Reversing The List.\n";
                    cout<<"Want to see reversed linked list(y/n):\n";
                    cin>>ch;
                    if(ch=='y')
                    {
                    l1.reverse();
                    }
                    cout<<"The linked list after reversing:-\n";
                    l1.display();
                    
                        break;
    
                    
            case 5: cout<<"\nExiting...";
                    exit(100);
                    break;
            default: cout<<"\nWrong input!!!";
                    break;
        }
        cout<<"\n\nReturn to menu(y/n): ";
        cin>>ch;
    }while(ch=='y');
    return 0;
}