C++ Programming Code Examples C++ > Data Structures Code Examples Program To Implement Doubly Linked List Program To Implement Doubly Linked List #include<iostream> #include<cstdio> #include<cstdlib> /* Node Declaration */ using namespace std; struct node { int info; struct node *next; struct node *prev; }*start; /* Class Declaration */ class double_llist { public: void create_list(int value); void add_begin(int value); void add_after(int value, int position); void delete_element(int value); void search_element(int value); void display_dlist(); void count(); void reverse(); double_llist() { start = NULL; } }; /* Main: Conatins Menu */ int main() { int choice, element, position; double_llist dl; while (1) { cout<<endl<<"----------------------------"<<endl; cout<<endl<<"Operations on Doubly linked list"<<endl; cout<<endl<<"----------------------------"<<endl; cout<<"1.Create Node"<<endl; cout<<"2.Add at begining"<<endl; cout<<"3.Add after position"<<endl; cout<<"4.Delete"<<endl; cout<<"5.Display"<<endl; cout<<"6.Count"<<endl; cout<<"7.Reverse"<<endl; cout<<"8.Quit"<<endl; cout<<"Enter your choice : "; cin>>choice; switch ( choice ) { case 1: cout<<"Enter the element: "; cin>>element; dl.create_list(element); cout<<endl; break; case 2: cout<<"Enter the element: "; cin>>element; dl.add_begin(element); cout<<endl; break; case 3: cout<<"Enter the element: "; cin>>element; cout<<"Insert Element after postion: "; cin>>position; dl.add_after(element, position); cout<<endl; break; case 4: if (start == NULL) { cout<<"List empty,nothing to delete"<<endl; break; } cout<<"Enter the element for deletion: "; cin>>element; dl.delete_element(element); cout<<endl; break; case 5: dl.display_dlist(); cout<<endl; break; case 6: dl.count(); break; case 7: if (start == NULL) { cout<<"List empty,nothing to reverse"<<endl; break; } dl.reverse(); cout<<endl; break; case 8: exit(1); default: cout<<"Wrong choice"<<endl; } } return 0; } /* Create Double Link List */ void double_llist::create_list(int value) { struct node *s, *temp; temp = new(struct node); temp->info = value; temp->next = NULL; if (start == NULL) { temp->prev = NULL; start = temp; } else { s = start; while (s->next != NULL) s = s->next; s->next = temp; temp->prev = s; } } /* Insertion at the beginning */ void double_llist::add_begin(int value) { if (start == NULL) { cout<<"First Create the list."<<endl; return; } struct node *temp; temp = new(struct node); temp->prev = NULL; temp->info = value; temp->next = start; start->prev = temp; start = temp; cout<<"Element Inserted"<<endl; } /* Insertion of element at a particular position */ void double_llist::add_after(int value, int pos) { if (start == NULL) { cout<<"First Create the list."<<endl; return; } struct node *tmp, *q; int i; q = start; for (i = 0;i < pos - 1;i++) { q = q->next; if (q == NULL) { cout<<"There are less than "; cout<<pos<<" elements."<<endl; return; } } tmp = new(struct node); tmp->info = value; if (q->next == NULL) { q->next = tmp; tmp->next = NULL; tmp->prev = q; } else { tmp->next = q->next; tmp->next->prev = tmp; q->next = tmp; tmp->prev = q; } cout<<"Element Inserted"<<endl; } /* Deletion of element from the list */ void double_llist::delete_element(int value) { struct node *tmp, *q; /*first element deletion*/ if (start->info == value) { tmp = start; start = start->next; start->prev = NULL; cout<<"Element Deleted"<<endl; free(tmp); return; } q = start; while (q->next->next != NULL) { /*Element deleted in between*/ if (q->next->info == value) { tmp = q->next; q->next = tmp->next; tmp->next->prev = q; cout<<"Element Deleted"<<endl; free(tmp); return; } q = q->next; } /*last element deleted*/ if (q->next->info == value) { tmp = q->next; free(tmp); q->next = NULL; cout<<"Element Deleted"<<endl; return; } cout<<"Element "<<value<<" not found"<<endl; } /* Display elements of Doubly Link List */ void double_llist::display_dlist() { struct node *q; if (start == NULL) { cout<<"List empty,nothing to display"<<endl; return; } q = start; cout<<"The Doubly Link List is :"<<endl; while (q != NULL) { cout<<q->info<<" <-> "; q = q->next; } cout<<"NULL"<<endl; } /* Number of elements in Doubly Link List */ void double_llist::count() { struct node *q = start; int cnt = 0; while (q != NULL) { q = q->next; cnt++; } cout<<"Number of elements are: "<<cnt<<endl; } /* Reverse Doubly Link List */ void double_llist::reverse() { struct node *p1, *p2; p1 = start; p2 = p1->next; p1->next = NULL; p1->prev = p2; while (p2 != NULL) { p2->prev = p2->next; p2->next = p1; p1 = p2; p2 = p2->prev; } start = p1; cout<<"List Reversed"<<endl; }
