Notes

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
struct student
{
char name[10];
int roll;
float per;
struct student * next;
}; // step1 creating a structure
typedef struct student node; //typedef as node and declaring functions
node* create_list();
void display(node *);
void insert(node ** head);
int count=0;

void insertAtBegining(node** headp); //insert and delete needs double pointer
void insertAtEnd(node ** headp);
void insertInbetween(node **headp);

void deletenode(node ** headp);
void deleteAtBegining(node **headp);
void deleteAtEnd(node ** headp);
void deleteInBetween(node ** headp);

void size();
int main(){
node * head;
int selection; //needs a node pointer
head=create_list();
printf(".............Linked List created with size=%dn",count); // assign value via create function
printf("tt******Enter your choicen"
" " 1" to display the linked Listn"
" "2" to insert a noden"
" "3" to delete a noden"
" "4" size of linkedlistn"
" "5" to quitn");
scanf("%d",&selection);

while (selection != 5)
{
switch (selection){
case 1:
display(head);
break;
case 2:
insert(&head);
break;
case 3:
deletenode(&head);
break;
case 4:
size();
break;
default:
printf("Invalid Entry");
break;
}
printf("tt********Enter your choicen"
" "1" to display the linked Listn"
" "2" to insert a noden"
" "3" to delete a noden"
" "4" size of linkedlistn"
" "5" to quitn");
scanf("%d",&selection);

}
return 0;
}
node * create_list(){

node * p,*head;
int n;
printf("Enter the number of nodes neededn"); //entering input from the user and looping
scanf("%d",&n);
for(int k=0;k<n;k++){
printf("ENter the name,roll and percentagen");
if (k==0)
{
head=(node *) malloc(sizeof(node)); //allocating dynamic memory
p=head; //copimg to p
}else{

p->next=(node *)malloc(sizeof(node)); //allocating next node dynalically
p=p->next; //initialising p->next
}
scanf("%s%d%f",p->name,&p->roll,&p->per);
}
p->next=NULL;
count=n;
return head;
}
void display(node * head){
node * p=head;
while(p!=NULL){
printf("Name is %s roll is %d and percentage is %fn",p->name,p->roll,p->per);
p=p->next;
}

}

void insert(node **headp){
int sel;
printf("tt ****Enter your choice n"
" " 1" you have to insert at the beginningn"
" "2" you have to insert at the endn"
" " 3" to insert in betweenn");
scanf("%d",&sel);
switch (sel){
case 1:
insertAtBegining(headp);
break;
case 2:
insertAtEnd(headp);
break;
case 3:
insertInbetween(headp);
break;
default :
printf("invalid Entry");
break;
}
count++;
}
void insertAtBegining(node **headp){

node * new1;
new1=(node *) malloc(sizeof(node));
printf ("enter the name roll and percentagen");
scanf("%s%d%f",new1->name,&new1->roll,&new1->per);
new1->next=(*headp);
*headp=new1;
}
void insertAtEnd(node ** headp){
node * pnode=*headp;
node * new2,*tailnode;
tailnode=*headp;
printf ("enter the name roll and percentagen");
scanf("%s%d%f",new2->name,&new2->roll,&new2->per);
while(tailnode->next!= NULL)
{
tailnode=tailnode->next;

}
new2->next=NULL;
tailnode->next=new2;


}

void insertInbetween(node ** headp){

node * new3,*refnode,*nextnode,*prenode;
// prenode= *headp;
nextnode=*headp;
// nextnode=prenode->next;
int refno;
printf("Enter before which roll number we have to add the new noden");
scanf("%d",&refno);
new3=(node *) malloc(sizeof(node));
while(nextnode!=NULL){

if(nextnode->roll == refno)
{ refnode=nextnode;
break;}
else{
refnode=NULL;
// printf("%d roll number does not exitn",refno);
}
prenode=nextnode;
nextnode=prenode->next;
}
printf ("Enter the name,roll and percentage of the new noden");
scanf("%s%d%f",new3->name,&new3->roll,&new3->per);
new3->next=refnode;
prenode->next=new3;
}
void deletenode(node ** headp){
printf("tt ********Enter choice *******n"
" "1" To delete the first noden"
" "2" To delete the end noden"
" "3" To delete an in between noden");
int sel;
scanf("%d",&sel);
switch(sel){
case 1:
deleteAtBegining(headp);
break;
case 2:
deleteAtEnd(headp);
break;
case 3:
deleteInBetween(headp);
break;
defaut:
printf("Invalid entryn");
break;

}

count--;

}
void deleteAtBegining(node ** headp){

node * temp =*headp;
*headp=(*headp)->next;
free(temp);

}
void deleteAtEnd(node ** headp){

node * tail =*headp;
node * pretail;
while(tail->next != NULL){
pretail=tail;
tail=tail->next;
}
pretail->next=NULL;
free(tail);

}
void deleteInBetween(node ** headp){
printf("Enter the roll no of the node to be deletedn" );
int delroll;
scanf("%d",&delroll);
node *temp=*headp;
node * previous;
while(temp->roll != delroll)
{
previous=temp;
temp=temp->next;
}
previous->next=temp->next;
free(temp);
}
void size(){
printf("The current size of linkedlist is %dn",count);

}