How to Create a linked list and perform various operations to be carried out on the linked list.

AIM: To create a linked list and perform various operationsto be carried out on the linked list.

AlGORITHM :

1. Start
2. Creating a node structure with two data members
3. Insertion at beginning:
4. Creating node
5. Checking for overflow condition if no overflow then set ptr->next=head and head = ptr
6. Insertion at end of list
7. If list is not overflow then defining a node pointer temp and initialize with head
8. Keep moving the temp to its next node until it reaches to the last node in the list (until temp → next is equal to NULL).
9. Set temp → next = ptr
   10.Deletion at beginning
10. Checking if list is empty or not if it is not empty then
11. ptr = head;
12. head = ptr->next;
13. free(ptr);
14. Deletion from end
15. If list is not empty then ptr = head;
16. while(ptr->next != NULL)
17. {
18. ptr1 = ptr;
19. ptr = ptr ->next;
20. }
21. ptr1->next = NULL;
22. free(ptr);
23. Displaying the list
24. If the list is not empty then define a node pointer ptr and initialize with head
25. Keep displaying ptr-> data until ptr reaches to the last node .
26. Stop

CODE:
#include<stdio.h>
#include<stdlib.h>
struct node
{
int data;
struct node *next;
};
struct node *head;

void beginsert ();
void lastinsert ();
void randominsert();
void begin_delete();
void last_delete();
void random_delete();
void display();
void search();
void main ()
{
int choice =0;
while(choice != 9)
{
printf("\nChoose the action to perform\n");
printf("\n1.Insert in begining\n2.Insert at last\n3.Insert at any random location\n4.Delete from Beginning\n5.Delete from last\n6.Delete node after specified location\n7.Search for an element\n8.Show\n9.Exit\n");
printf("\nEnter your choice?\n");
scanf("\n%d",&choice);
switch(choice)
{
case 1:
beginsert();
break;
case 2:
lastinsert();
break;
case 3:
randominsert();
break;
case 4:
begin_delete();
break;
case 5:
last_delete();
break;
case 6:
random_delete();
break;
case 7:
search();
break;
case 8:
display();
break;
case 9:
exit(0);
break;
default:
printf("Please enter your choice");
}
}
}
void beginsert()
{
struct node *ptr;
int item;
ptr = (struct node *) malloc(sizeof(struct node *));
if(ptr == NULL)
{
printf("\nOVERFLOW");
}
else
{
printf("\nEnter value\n");
scanf("%d",&item);
ptr->data = item;
ptr->next = head;
head = ptr;
printf("\nNode inserted");
}

}
void lastinsert()
{
struct node ptr,temp;
int item;
ptr = (struct node*)malloc(sizeof(struct node));
if(ptr == NULL)
{
printf("\nOVERFLOW");
}
else
{
printf("\nEnter value\n");
scanf("%d",&item);
ptr->data = item;
if(head == NULL)
{
ptr -> next = NULL;
head = ptr;
printf("\nNode inserted");
}
else
{
temp = head;
while (temp -> next != NULL)
{
temp = temp -> next;
}
temp->next = ptr;
ptr->next = NULL;
printf("\nNode inserted");

    }
}

}
void randominsert()
{
int i,loc,item;
struct node *ptr, *temp;
ptr = (struct node *) malloc (sizeof(struct node));
if(ptr == NULL)
{
printf("\nOVERFLOW");
}
else
{
printf("\nEnter element value: ");
scanf("%d",&item);
ptr->data = item;
printf("\nEnter the location after which you want to insert ");
scanf("\n%d",&loc);
temp=head;
for(i=0;i<loc;i++)
{
temp = temp->next;
if(temp == NULL)
{
printf("\ncan't insert\n");
return;
}

    }
    ptr ->next = temp ->next;
    temp ->next = ptr;
    printf("\nNode inserted");
}

}
void begin_delete()
{
struct node *ptr;
if(head == NULL)
{
printf("\nList is empty\n");
}
else
{
ptr = head;
head = ptr->next;
free(ptr);
printf("\nNode deleted from the begining \n");
}
}
void last_delete()
{
struct node ptr,ptr1;
if(head == NULL)
{
printf("\nlist is empty");
}
else if(head -> next == NULL)
{
head = NULL;
free(head);
printf("\nOnly node of the list deleted\n");
}

else
{
    ptr = head;
    while(ptr->next != NULL)
    {
        ptr1 = ptr;
        ptr = ptr ->next;
    }
    ptr1->next = NULL;
    free(ptr);
    printf("\nDeleted Node from the last\n");
}

}
void random_delete()
{
struct node ptr,ptr1;
int loc,i;
printf("\n Enter the location of the node after which you want to perform deletion \n");
scanf("%d",&loc);
ptr=head;
for(i=0;i<loc;i++)
{
ptr1 = ptr;
ptr = ptr->next;

    if(ptr == NULL)
    {
        printf("\nCan't delete");
        return;
    }
}
ptr1 ->next = ptr ->next;
free(ptr);
printf("\nDeleted node %d ",loc+1);

}
void search()
{
struct node *ptr;
int item,i=0,flag;
ptr = head;
if(ptr == NULL)
{
printf("\nEmpty List\n");
}
else
{
printf("\nEnter item which you want to search\n");
scanf("%d",&item);
while (ptr!=NULL)
{
if(ptr->data == item)
{
printf("item found at location %d ",i+1);
flag=0;
}
else
{
flag=1;
}
i++;
ptr = ptr -> next;
}
if(flag==1)
{
printf("Item not found\n");
}
}

}

void display()
{
struct node *ptr;
ptr = head;
if(ptr == NULL)
{
printf("Nothing to print");
}
else
{
printf("\nprinting values\n");
while (ptr!=NULL)
{
printf("\n%d",ptr->data);
ptr = ptr -> next;
}
}
}