Write a program to perform data structure operations on LInked list. ~ Era Of Skills

#include<stdio.h>
#include<stdlib.h>
struct node
{
int data;
struct node *next;
};
main()
{
struct node *start,*loc;
int c,ch,f=0;
int n,item;
void create(struct node **, int);
void show(struct node *);

void insert_beg(struct node **);
void insert_end(struct node **);
void insert_after(struct node *);
void insert_before(struct node **);
void insert_sorted(struct node **);

void deletion_beg(struct node **);
void deletion_end(struct node **);
void deletion_after(struct node *);
void deletion_before(struct node **);
void deletion_given(struct node **);

extern struct node* search_unsorted(struct node *,int);
extern struct node* search_item(struct node *,int );
extern struct node* search_bitem(struct node *,int );
struct node* search_sorted(struct node *,int);
extern struct node* search_bi(struct node *,int );
start=NULL;

printf("main menu");
printf("\nPress 1 to create a linked list");
while(f!=6)
{
printf("\nPress 2 to display a linked list");
printf("\nPress 3 to insert a item linked list");
printf("\nPress 4 to search a item linked list");
printf("\nPress 5 to delete a item linked list");
printf("\npress 6 to exit");
printf("\nEnter your choice");
scanf("%d",&ch);
switch(ch)
{
case 1:
printf("Enter the elements you want in your linked list :");
scanf("%d",&n);
create(&start,n);
break;
case 2:
show(start);
break;
case 3:
printf("\ninsert Menu:");
printf("\nPress 1 to insert item in the begining");
printf("\nPress 2 to insert item in the last");
printf("\nPress 3 to insert item after the given item");
printf("\nPress 4 to insert item before the given item");
printf("\nPress 5 to insert item in the sorted linked list");
printf("\nEnter your choice");
scanf("%d",&c);
switch(c)
{

case 1:
insert_beg(&start);
break;
case 2:
insert_end(&start);
break;
case 3:
insert_after(start);
break;
case 4:
insert_before(&start);
break;
case 5:
insert_sorted(&start);
break;
default:
printf("Invalid choice");
}
break;
case 4:
printf("\nEntered the item to be searched:");
scanf("%d",&item);
printf("\nsearching Menu:");
printf("\nPress 1 to search item in the unsorted linked list");
printf("\nPress 2 to search item in the sorted linked list");
printf("\nEnter your choice");
scanf("%d",&c);
switch(c)
{
case 1:
loc=(struct node *)search_unsorted(start,item);
if(loc==NULL)
printf("\nItem is not in the list");
else
printf("\nitem is at %d location",loc);
break;
case 2:
loc=(struct node *)search_sorted(start,item);
if(loc==NULL)
printf("\nItem is not in the list");
else
printf("\nitem is at %d location",loc);
break;
default:
printf("Invalid choice");
}
break;
case 5:
printf("\ndeletion Menu:");
printf("\nPress 1 to delete item in the begining");
printf("\nPress 2 to delete item in the last");
printf("\nPress 3 to delete item after the given item");
printf("\nPress 4 to delete item before the given item");
printf("\nPress 5 to delete given item ");
printf("\nEnter your choice");
scanf("%d",&c);
switch(c)
{

case 1:
deletion_beg(&start);
break;
case 2:
deletion_end(&start);
break;
case 3:
deletion_after(start);
break;
case 4:
deletion_before(&start);
break;
case 5:
deletion_given(&start);
break;
default:
printf("Invalid choice");
}
break;
break;
case 6:
f=6;
break;
default:
printf("Invalid choice");
}
}
}

void create(struct node **q,int n)
{
int i;
struct node *lst;
struct node *p;
lst=NULL;
for(i=1;i<=n;i++)
{
p=(struct node *)malloc(sizeof(struct node));
printf("Enter the %d element :",i);
scanf("%d",&(p->data));
p->next=NULL;
if(*q==NULL)
*q=p;
else
lst->next=p;
lst=p;
}
}

void show(struct node *start)
{
printf("Entered linked list is :\n");
while(start!=NULL)
{
printf(" %d\n",start->data);
start=start->next;
}
}

void insert_beg(struct node **q)
{
struct node *p;
p=(struct node *)malloc(sizeof(struct node));
printf("Enter the element to be inserted ");
scanf("%d",&(p->data));
p->next=*q;
*q=p;
}

void insert_end(struct node **q)
{
struct node *p,*ptr;
p=(struct node *)malloc(sizeof(struct node));
printf("Enter the element to be inserted ");
scanf("%d",&(p->data));
p->next=NULL;
if(*q==NULL)
{
*q=p;
}
else
{
ptr=*q;
while(ptr->next!=NULL)
{
ptr=ptr->next;
}
ptr->next=p;
}
}

void insert_after(struct node *q)
{
struct node *p,*loc;
int item;
printf("Enter the item after which new element is to be inserted ");
scanf("%d",&item);
loc=(struct node *)search_unsorted(q,item);
if(loc==NULL)
printf("\nItem afer which element is to be inserted is not in the list");
else
{
p=(struct node *)malloc(sizeof(struct node));
printf("Enter the element to be inserted ");
scanf("%d",&(p->data));
p->next=loc->next;
loc->next=p;
}
}

void insert_before(struct node **q)
{
struct node *p,*loc;
int item;
printf("Enter the item before which new element is to be inserted ");
scanf("%d",&item);
if(*q==NULL)
{
printf("\nItem before which element is to be inserted is not in the list");
return;
}

p=(struct node *)malloc(sizeof(struct node));
printf("Enter the element to be inserted ");
scanf("%d",&(p->data));

if(item==(*q)->data)
{
p->next=*q;
*q=p;
}
else
{
loc=(struct node *)search_bitem(*q,item);
if(loc==NULL)
printf("\nItem before which element is to be inserted is not in the list");
else
{
p->next=loc->next;
loc->next=p;
}
}
}

struct node* search_bitem(struct node *start,int item)
{
struct node *prev,*ptr;
ptr=start;
prev=ptr;
ptr=ptr->next;
while(ptr!=NULL)
{
if(item==(ptr->data))
return prev;
prev=ptr;
ptr=ptr->next;
}
return NULL;
}

void insert_sorted(struct node **start)
{
struct node *p,*loc;
int item;
p=(struct node *)malloc(sizeof(struct node));
printf("Enter the element to be inserted ");
scanf("%d",&item);
p->data=item;
p->next=NULL;
loc=(struct node *)search_item(*start,item);
if(loc==NULL)
{
p->next=*start;
*start=p;
}
else
{
p->next=loc->next;
loc->next=p;
}
}

struct node* search_item(struct node *ptr,int item)
{
struct node *prev;
if(ptr==NULL)
return NULL;
else if(item<(ptr->data))
return NULL;
prev=ptr;
ptr=ptr->next;
while(ptr!=NULL)
{
if(item<(ptr->data))
return prev;
prev=ptr;
ptr=ptr->next;
}
return prev;
}

struct node* search_unsorted(struct node *ptr,int item)
{
while(ptr!=NULL)
{
if(item==ptr->data)
return ptr;
else
ptr=ptr->next;
}
return NULL;
}

struct node* search_sorted(struct node *ptr,int item)
{
struct node* loc=NULL;
while(ptr!=NULL)
{
if(item>ptr->data)
ptr=ptr->next;
else if(item==ptr->data)
{ loc=ptr;
break;}
else
break;
}
return loc;
}

void deletion_beg(struct node **start)
{
struct node *temp;
if(*start==NULL)
{
printf("\n list is already empty");
}
else
{
temp=*start;
*start=(*start)->next;
free(temp);
}
}
void deletion_end(struct node **start)
{
struct node *temp,*prev,*ptr;
ptr=*start;
if(ptr==NULL)
{
printf("\n list is already empty");
}
else if(ptr->next==NULL)
{
temp=ptr;
ptr=ptr->next;
*start=ptr;
free(temp);
return;
}
else
{
prev=ptr;
ptr=ptr->next;
while(ptr->next!=NULL)
{
prev=ptr;
ptr=ptr->next;
}
temp=prev->next;
prev->next=NULL;
free(temp);
}
}
void deletion_after(struct node *start)
{
struct node *temp,*loc;
int item;
printf("Enter the item after which new element is to be deleted ");
scanf("%d",&item);
loc=(struct node *)search_unsorted(start,item);
if(loc==NULL)
{
printf("\nItem afer which element is to be deleted is not in the list");
return;
}
if(loc->next==NULL)
{
printf("\nNo element exit after the given item");
return;
}
temp=loc->next;
loc->next=(loc->next)->next;
free(temp);
}

void deletion_given(struct node **start)
{
struct node *temp,*loc;
int item;
printf("Enter the item to be deleted ");
scanf("%d",&item);
if(*start==NULL)
{
printf("\nlist is empty");
return;
}
if(item==(*start)->data)
{
temp=*start;
*start=(*start)->next;
free(temp);
}
else
{
loc=(struct node *)search_bitem(*start,item);
if(loc==NULL)
printf("\nItem which is to be deleted is not in the list");
else
{
temp=loc->next;
loc->next=temp->next;
free(temp);
}
}
}

void deletion_before(struct node **start)
{
struct node *temp,*loc;
int item;
printf("Enter the item before which the element is to be deleted ");
scanf("%d",&item);
if(*start==NULL)
{
printf("\nlist is empty");
}
else if(item==(*start)->data)
{
printf("\nNo element exits before given item");
}
else if(item==((*start)->next)->data)
{
temp=*start;
*start=(*start)->next;
free(temp);
}
else
{
loc=(struct node *)search_bi(*start,item);
if(loc==NULL)
printf("\nItem before which element is to be deleted is not in the list");
else
{
temp=loc->next;
loc->next=temp->next;
free(temp);
}
}
}

struct node* search_bi(struct node *start,int item)
{
struct node *p1,*p2,*c;
p1=start;
p2=p1->next;
c=p2->next;
while(c!=NULL)
{
if(c->data==item)
return p1;
p1=p2;
p2=c;
c=c->next;
}
return NULL;
}