Notes

#include<stdio.h>
#include<conio.h>
#include<malloc.h> //for malloc function
#include<process.h> //fpr exit function
struct node
{
int info;
struct node *next;
};

typedef struct node NodeType;
NodeType *head;
//head=NULL;
void insert_atfirst(int);
void insert_givenposition(int);
void insert_atend(int);
void delet_first();
void delet_last();
void delet_nthnode();
void info_sum();
void count_nodes();
int main()
{
int choice;
int item;
//clrscr();
do
{
printf("nnnn------------------- Manu for Linked List Program:---------------------n");
printf("1. insert first n2.insert at given position n3 insert at last n4:Delete first node n5:delete last node n6:delete nth node n7:Display items n8count nodes n9:exitn");
printf("enter your choicen");
scanf("%d",&choice);
switch(choice)
{
case 1:
printf("Enter item to be inserted");
scanf("%d",&item);
insert_atfirst(item);
break;

case 2:
printf("Enter 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:
delet_first();
break;
case 5:
delet_last();
break;

case 6:
delet_nthnode();
break;

case 7:
info_sum();
break;

case 8:
count_nodes();
break;

case 9:
exit(1);
break;

default:
printf("invalid choicen");
break;
}
}while(choice<10);
getch();
}

/************function definitions**************/
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 delet_first()
{
NodeType *temp;
if(head==NULL)
{
printf("Void deletion|n");
return;
}
else
{
temp=head;
head=head->next;
free(temp);
}
}

void delet_last()
{
NodeType *hold,*temp;
if(head==NULL)
{
printf("Void deletion|n");
return;
}
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 delet_nthnode()
{
NodeType *hold,*temp;
int pos, i;
if(head==NULL)
{
printf("Void deletion|n");
return;
}
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);
}