//C program

//replace the question marks in the template and

//write the code for adding the nodes

#include

#include

struct Node

{

struct Node *next, *prev;

int data;

};

void print_list(struct Node *head);

void print_backwards(struct Node *head, struct Node *tail);

void sort_list(struct Node *head);

void search_list (struct Node *head);

struct Node* search_delete (struct Node *head, struct Node *tail);

struct Node* place_tail(struct Node *head);

struct Node* add_node(struct Node *head, struct Node *tail);

void main()

{

struct Node *temp, *head, *tail;

int size, i;

printf("How many numbers do you want to enter? ");

scanf("%d", &size);

printf("Enter %d numbers ", size);

temp=(struct Node*)malloc(sizeof(struct Node));

scanf("%d", &temp->data);

temp->next=NULL;

temp->prev=NULL;

head=temp;

tail=temp;

for(i=0; i

{

temp=(struct Node*)malloc(sizeof(struct Node));

scanf("%d", &temp->data);

temp->next=NULL;

temp->prev=NULL;

tail->next=temp;

temp->prev=tail;

tail=tail->next;

}

print_list(head);

print_backwards(head, tail);

tail=place_tail(head);

print_list(head);

print_backwards(head, tail);

//sort_list(head);

print_list(head);

search_list(head);

head=search_delete(head, tail);

tail=place_tail(head);

print_list(head);

print_backwards(head, tail);

head= add_node(head, tail);

tail=place_tail(head);

print_list(head);

print_backwards(head, tail);

printf("Sorting the list ");

sort_list(head);

print_list(head);

print_backwards(head, tail);

}

void print_list(struct Node *head)

{

struct Node *temp;

printf("Printing the list ");

for(temp=head; temp!=NULL; temp=temp->next)

printf("%d ", temp->data);

printf(" ");

}

void print_backwards(struct Node *head, struct Node *tail)

{

struct Node *temp;

printf("Printing the list backwards ");

for(temp=tail; temp!=NULL; temp=temp->prev)

printf("%d ", temp->data);

printf(" ");

}

void sort_list(struct Node *head)

{

struct Node *temp, *temp1;

int storage;

printf("Sorting the list ");

for(temp1=head; temp1->next!=NULL; temp1=temp1->next)

for(temp=head; temp->next!=NULL; temp=temp->next)

{

if(temp->data > temp->next->data)

{

storage=temp->data;

temp->data=temp->next->data;

temp->next->data=storage;

}

}

}

void search_list (struct Node *head)

{

int found=0;

struct Node *temp;

int target;

printf("Please enter a number you want to search for ");

scanf("%d", &target);

for(temp=head; temp!=NULL && found!=1; temp=temp->next)

if(temp->data==?)

found=1;

if(found==?)

printf("The number is found ");

else

printf("The number is not found ");

printf(" ");

}

struct Node* search_delete (struct Node *head, struct Node *tail)

{

int found=0;

struct Node *temp, *above, *below;

int target;

printf("Please enter a number you want to delete from the list ");

scanf("%d", &target);

for(temp=head; temp!=NULL && found!=1; )

if(temp->data==?)

found=1;

else

temp=temp->next;

if(found==1)

{

if(temp==head)

{

//move head down to point to the next node

head->prev=NULL;

free(temp);

}

else

{

if(temp==tail)

{

//move tail up to point to previous node

tail->next=NULL;

free(temp);

}

else

{

above=?

below=?

above->next=?

below->prev=?

free(temp);

}

}

}

else

printf("The number is not in the list ");

return head;

}

struct Node* place_tail(struct Node *head)

{

struct Node *temp;

for(temp=head; temp->next!=NULL; )

temp=temp->next;

return temp;

}

struct Node* add_node(struct Node *head, struct Node *tail)

{

struct Node *temp;

char input;

printf("Enter the number you want to add to the list ");

temp=(struct Node*)malloc(sizeof(struct Node));

scanf("%d", &temp->data);

temp->next=NULL;

temp->prev=NULL;

printf("Where do you want to place youe new node? Enter 't' for the top of the list and 'b'-for the bottom ");

scanf(" %c", &input);

if(input=='t')

{

//code for inserting a node on the top

}

else

{

//code for inserting a node at the bottom

}

return head;

}