Linked List (C++)

#include
#include
#include


class list
{
struct node
{
int data;
node *link;
}*p;
public:
void inslast(int);
void insbeg(int);
void insnext(int,int);
void delelement(int);
void delbeg();
void dellast();
void disp();
int seek(int);
list(){p=NULL;}
~list();
};

void list::inslast(int x)
{
node *q,*t;
if(p==NULL)
{
p=new node;
p->data=x;
p->link=NULL;
}
else
{
q=p;
while(q->link!=NULL)
q=q->link;
t=new node;
t->data=x;
t->link=NULL;
q->link=t;
}
cout<<"
Inserted successfully at the end..
";
disp();
}

void list:: insbeg(int x)
{
node *q;
q=p;
p=new node;
p->data=x;
p->link=q;
cout<<"
Inserted successfully at the begining..
";
disp();
}


void list::delelement(int x)
{
node *q,*r;
q=p;
if(q->data==x)
{
p=q->link;
delete q;
return;
}
r=q;
while(q!=NULL)
{
if(q->data==x)
{
r->link=q->link;
delete q;
return;
}
r=q;
q=q->link;
}
cout<<"
Element u entered "<";
}

void list:: delbeg()
{
cout<<"
The list before deletion:
";
disp();
node *q;
q=p;
if(q==NULL)
{
cout<<"
No data is present..
";
return;
}
p=q->link;
delete q;
return;
}


void list:: dellast()
{
cout<<"
The list before deletion:
";
disp();
node *q,*t;
q=p;
if(q==NULL)
{
cout<<"
There is no data in the list..
";
return;
}
if(q->link==NULL)
{
p=q->link;
delete q;
return;
}

while(q->link->link!=NULL)
q=q->link;
q->link=NULL;
return;
}

list::~list()
{
node *q;
if(p==NULL) return;
while(p!=NULL)
{
q=p->link;
delete p;
p=q;
}
}

void list::disp()
{
node *q;
q=p;
if(q==NULL)
{
cout<<"
No data is in the list..
";
return;
}
cout<<"
The items present in the list are :
";
while(q!=NULL)
{
cout<<" "<data;
q=q->link;
}
}

void list :: insnext(int value,int position)
{
node *temp,*temp1;
temp=p;
if(temp1==NULL)
{
temp1= new node;
temp1->data=value;
temp1->link=NULL;
p=temp1;
return;
}
for(int i=0;((ilink!=NULL)) ;i++)
{
if(i==(position-1))
{
temp1= new node;
temp1->data= value;
temp1->link=temp->link;
temp->link=temp1;
}
temp=temp->link;
}
//cout<<"
Inserted successfully at the position.."< disp();
}


int list::seek(int value)
{
node *temp;
temp=p;
int position=0;
while(temp!=NULL)
{
if(temp->data==value)
return position+1;
else
{
temp=temp->link;
position=position+1;
}
}
cout<<"

Element "< return 0;
}


void main()
{
list l;
int ch,v,p,ps;
do
{
clrscr();
cout<<"
Operations on List..
";
cout<<"
1.Insertion
2.Deletion
3.Display
4.Seek
5.Exit";
cout<<"
Enter ur choice:";
cin>>ch;

switch(ch)
{
case 1:
cout<<"
1.Insertion at begining
2.Insertion at the end
";
cout<<"3.Insertion after the mentioned position
";
cout<<"
Enter ur choice:";
cin>>ps;
cout<<"
Enter the value to insert:";
cin>>v;
switch(ps)
{
case 1:
l.insbeg(v);
break;
case 2:
l.inslast(v);
break;
case 3:
cout<<"
Enter the position to insert the value:";
cin>>p;
l.insnext(v,p);
break;

default:
cout<<"
The choice is invalid
";
return;
}
break;

case 2:
cout<<"
1.Delete the first element
2.Delete the last element";
cout<<"
3.Enter the element to delete from the list";
cout<<"
Enter ur choice:";
cin>>ps;
switch(ps)
{
case 1:
l.delbeg();
cout<<"
The list after deletion:
";l.disp();
break;
case 2:
l.dellast();
cout<<"
The list after deletion:
";l.disp();
break;
case 3:
l.disp();
cout<<"
Enter the element to delete : ";
cin>>v;
l.delelement(v);
cout<<"
The list after deletion:
";l.disp();
break;

default:
cout<<"
The option is invalid...
";
break;
}
break;

case 3:
l.disp();
break;

case 4:
l.disp();
cout<<"
Enter the element to search:";
cin>>v;
cout<<"
The position of the element "<< v<<" is "< getch();
break;

case 5:
exit(1);

default:
cout<<"
The option is invalid...
";
return;
}
getch();
}while(ch!=5);
getch();
return;
}