Notes

//Write a program to implement link list
#include<stdio.h>
#include<stdlib.h>
#include<malloc.h>
typedef struct node{
int info;
struct node *next;
}nodetype;
nodetype *head;
//head=NULL
void insert_atfirst(int);
void insert_givenposition(int);
void insert_atend(int);
void del_first();
void del_last();
void del_nthnode();
void info_sum();
void count_nodes();
void main(){
int choice,item;
do{
printf("nnn-------------Menu for Linked List Program-------------n");
printf("n1.Insert first n2. Insert at given position n3. Insert at last n4. del first node");
printf("n5. del the last node n6. del the nth node n7. Display items n8. Count nodes n9. exitn");
printf("nEnter the choice:");
scanf("%d",&choice);
switch(choice){
case 1:
printf("Enter the item to be inserted:");
scanf("%d",&item);
insert_atfirst(item);
break;
case 2:
printf("Enter the item to be inserted:");
scanf("%d",&item);
insert_givenposition(item);
break;
case 3:
printf("Enter item to be inserted:");
scanf("%d",&item);
insert_atend(item);
break;
case 4:
del_first();
break;
case 5:
del_last();
break;
case 6:
del_nthnode();
break;
case 7:
info_sum();
break;
case 8:
count_nodes();
break;
case 9:
exit(0);
default:
printf("nnINVALID DATA ENTRYn");
}
}while(choice!=9);
}
//function definition
void insert_atfirst(int item){
nodetype *nnode;
nnode=(nodetype*)malloc(sizeof(nodetype));
nnode->info=item;
nnode->next=head;
head=nnode;
}
void insert_givenposition(int item){
nodetype *nnode;
nodetype *temp;
temp=head;
int p,i;
nnode=(nodetype*)malloc(sizeof(nodetype));
nnode->info=item;
if(head==NULL){
nnode->next=NULL;
head=nnode;
}
else{
printf("Enter position of a node at which you want to insert an new noden");
scanf("%d",&p);
for(i=1;i<p-1;i++){
temp=temp->next;
}
nnode->next=temp->next;
temp->next=nnode;
}
}
void insert_atend(int item){
nodetype *nnode;
nodetype *temp;
temp=head;
nnode=(nodetype*)malloc(sizeof(nodetype));
nnode->info=item;
if(head==NULL){
nnode->next=NULL;
head=nnode;
}
else{
while(temp->next!=NULL){
temp=temp->next;
}
nnode->next=NULL;
temp->next=nnode;
}
}
void del_first(){
nodetype *temp;
if(head==NULL){
printf("Void deletionn");
}
else{
temp=head;
head=head->next;
free(temp);
}
}
void del_last(){
nodetype *hold,*temp;
if(head==NULL){
printf("Void deletionn");
}
else if(head->next==NULL){
hold=head;
head=NULL;
free(hold);
}
else{
temp=head;
while(temp->next->next!=NULL){
temp=temp->next;
}
hold=temp->next;
temp->next=NULL;
free(hold);
}
}
void del_nthnode(){
nodetype *hold,*temp;
int pos,i;
if(head==NULL){
printf("Void deletionn");
}
else{
temp=head;
printf("Enter position of node which node is to be deletedn");
scanf("%d",&pos);
for(i=1;i<pos-1;i++){
temp=temp->next;
}
hold=temp->next;
temp->next=hold->next;
free(hold);
}
}
void info_sum(){
nodetype *temp;
temp=head;
while(temp!=NULL){
printf("%dt",temp->info);
temp=temp->next;
}
}
void count_nodes(){
int cnt=0;
nodetype *temp;
temp=head;
while(temp!=NULL){
cnt++;
temp=temp->next;
}
printf("Total nodes=%d",cnt);
}