Firoz Ansari wrote...

/*******************************************************************
** @author firoz **
** **
** **
** Description: A program to: **
** **
** 1)INSERT **
** at first position, last position and arbitrary position. **
** 2)TRAVERSE **
** 3)DELETE **
** at first position, last position and arbitrary position. **
** 4)SORT **
** **
** the elements in a LINKED LIST. **
*******************************************************************/

#include<stdio.h>
#include<stdlib.h>

typedef struct node
{
int data;
struct node *next;
} *Node;

/////////////////////////////
Node insertFront( Node head )
{
Node temp;
char choice;
do{
printf("\nEnter the Element in the linked list:\n");
temp=(Node)malloc(sizeof(struct node));
scanf("%d",&temp->data);
temp->next=head;
head=temp;
printf("%d Entered at front\nWanna insert more data in the front?(Y/N) :",head->data);
scanf("\n %c",&choice);
}while(choice=='y'||choice=='Y');

return head;
}

//////////////////////////////
void traverse(Node head){
Node temp;
temp = head;
printf("\n***Traversing the Linked List:***\n");
while(temp!=NULL){
printf("%d-> ",temp->data);
temp=temp->next;
}
printf("NULL\n");
}

//////////////////////////
Node insertBack(Node head){
Node temp, tail;
char choice;
tail = head;
if(head==NULL){
printf("Linked list is empty, therefore inserting the node at first position:\n");
head=insertFront(head);
}
else{
while(tail->next!=NULL)
tail=tail->next;
do{
temp=(Node)malloc(sizeof(struct node));
printf("\nEnter Element of Linked list\n");
scanf("%d",&temp->data);
temp->next=NULL;
tail->next=temp;
tail=tail->next;
printf("%d is inserted at end\nWanna Insert more data at end(Y/N)?",tail->data);
scanf("\n%c",&choice);
}while(choice=='y'||choice=='Y');
}
return head;
}

/////////////////////////////
Node insertPosition(Node head){
int i, n;
char choice;
Node temp, position;
do{
position=head;
printf("Enter the position at which you want to insert the data\n");
scanf("%d",&n);
if(n==1)
head=insertFront(head);
else{
for(i=2; i<n && position!=NULL ; i++)
position=position->next;
if(position==NULL){
printf("Invalid position for insertion !\n Press Enter to Continue.....\t");
fflush(stdin);
getchar();
getchar();
}
else{
temp=(Node)malloc(sizeof(struct node));
printf("Enter the data to be inserted at position %d:\t",n);
scanf("%d",&temp->data);
temp->next = position -> next;
position->next = temp;
printf("%d is inserted at position %d",position->next->data, n);
}
}
printf("\nDo wanna insert more data at arbitary position?(Y/N)\n");
scanf("\n%c",&choice);
}while(choice=='y'||choice=='Y');
return head;
}

//////////////////////
Node deleteFront(Node head){
Node temp;
temp=head;
head=temp->next;
free(temp);
return head;
}

//////////////////////
Node deleteBack(Node head){
Node temp, old_temp;
temp=head;
old_temp=temp;
while(temp->next!=NULL){
old_temp=temp;
temp=temp->next;
}
if(head->next==NULL)
head=NULL;
old_temp->next=NULL;
free(temp);
return head;
}

/////////////////////
Node deletePosition(Node head,int n){
Node temp, old_temp;
temp=head;
old_temp=temp;
int i;
if(n==1){
head=deleteFront(head);
printf("data at position %d is deleted\n",n);
}
else{
for(i=1;i<n && temp!=NULL;i++){
old_temp=temp;
temp=temp->next;
}
if(temp==NULL){
printf("Invalid position for deletion!\n");
}
else{
old_temp->next=temp->next;
free(temp);
printf("data at position %d is deleted\n",n);
}
}
return head;
}

/////////////////////////
void sort(Node head){
int temp=0;
Node temp1, temp2;
for( temp1 = head; temp1 != NULL; temp1 = temp1->next)
for(temp2=temp1->next; temp2 != NULL; temp2 = temp2->next)
if( temp1->data > temp2->data){
temp = temp1->data;
temp1->data = temp2->data;
temp2->data = temp;
}
printf("***Now the linked list is sorted***\nThe Sorted list is::\n");
traverse(head);
}

int main()
{
int select, n;
Node head=NULL;
char choice;
printf("\n\n***Hi! Welcome to the program of making linked list***\n");

do{
printf("Press 1 to Insert:\n");
printf("Press 2 to Traverse:\n");
printf("Press 3 to Delete:\n");
printf("Press 4 to Sort:\n");
scanf("%d",&select);

if(select==1){
//code for insert
printf("\nPress 1 to Insert at Front:\n");
printf("Press 2 to Insert at Back:\n");
printf("Press 3 to Insert at Specific position:\n");
scanf("%d",&n);
switch(n){
case 1:
//insert at front
head=insertFront(head);
break;
case 2:
//insert at back
head=insertBack(head);
break;
case 3:
//insert at specific position
head=insertPosition(head);
break;
default :
printf("Wrong choice\n");
}
}
else if(select==2){
//code for Traverse
traverse(head);
}
else if(select==3){
if(head!=NULL){
//cade for Delete
printf("\nPress 1 to Delete at Front:\n");
printf("Press 2 to Delete at Back:\n");
printf("Press 3 to Delete at Specific position:\n");
scanf("%d",&n);
switch(n){
case 1:
//insert at front
head=deleteFront(head);
printf("First Node is deleted\n");
break;
case 2:
//insert at back
head=deleteBack(head);
printf("Last Node is deleted\n");
break;
case 3:
//insert at specific position
printf("Enter the position at which data is to be deleted\n");
scanf("\n%d",&n);
if(n==1)
head=deleteFront(head);
else
head=deletePosition(head, n);
break;
default :
printf("Wrong choice\n");
}
}
else{
printf("The linked list is already empty!!!\n");
}
}
else if(select==4){
//code for sort
sort(head);
}
else{
printf("\nYou have Entered Wrong option, Try again::\n\n");
choice='y';
continue;
}
printf("\nDo you want to continue in Linked list Program?\nPress Y for Yes and N for No::\n");
scanf("\n");
choice=getchar();
}while(choice=='y'||choice=='Y');
return 0;
}