C program to create a linked list and perform insertions and deletions of all cases and Write functions to sort and finally delete the entire list at once

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <malloc.h>
struct node
{
int data;
struct node *next;
};
struct node *start = NULL;
struct node *create_ll(struct node *);
struct node *display(struct node *);
struct node *insert_beg(struct node *);
struct node *insert_end(struct node *);
struct node *insert_before(struct node *);
struct node *insert_after(struct node *);
struct node *delete_beg(struct node *);
struct node *delete_end(struct node *);
struct node *delete_node(struct node *);
struct node *delete_after(struct node *);
struct node *delete_list(struct node *);
struct node *sort_list(struct node *);
int main(int argc, char *argv[]) {
int option;
do
{
 printf(“\n\n *****MAIN MENU *****”);
 printf(“\n 1: Create a list”);
 printf(“\n 2: Display the list”);
 printf(“\n 3: Add a node at the beginning”);
 printf(“\n 4: Add a node at the end”);
 printf(“\n 5: Add a node before a given node”);
 printf(“\n 6: Add a node after a given node”);
 printf(“\n 7: Delete a node from the beginning”);

printf(“\n 8: Delete a node from the end”);
 printf(“\n 9: Delete a given node”);
 printf(“\n 10: Delete a node after a given node”);
 printf(“\n 11: Delete the entire list”);
 printf(“\n 12: Sort the list”);
 printf(“\n 13: EXIT”);
 printf(“\n\n Enter your option : “);
 scanf(“%d”, &option);
 switch(option)
 {
 case 1: start = create_ll(start);
 printf(“\n LINKED LIST CREATED”);
 break;
 case 2: start = display(start);
 break;
 case 3: start = insert_beg(start);
 break;
 case 4: start = insert_end(start);
 break;
 case 5: start = insert_before(start);
 break;
 case 6: start = insert_after(start);
 break;
 case 7: start = delete_beg(start);
 break;
 case 8: start = delete_end(start);
 break;
 case 9: start = delete_node(start);
 break;
 case 10: start = delete_after(start);
 break;
 case 11: start = delete_list(start);
 printf(“\n LINKED LIST DELETED”);
 break;
 case 12: start = sort_list(start);
 break;
 }
}while(option !=13);
getch();
return 0;
}
struct node *create_ll(struct node *start)
{
struct node *new_node, *ptr;
int num;
printf(“\n Enter -1 to end”);
printf(“\n Enter the data : “);
scanf(“%d”, &num);
while(num!=-1)
{
 new_node = (struct node*)malloc(sizeof(struct node));
 new_node -> data=num;
 if(start==NULL)
 {
 new_node -> next = NULL;
 start = new_node;
 }
 else
 {
 ptr=start;

while(ptr->next!=NULL)
 ptr=ptr->next;
 ptr->next = new_node;
 new_node->next=NULL;
 }
 printf(“\n Enter the data : “);
 scanf(“%d”, &num);
}
return start;
}
struct node *display(struct node *start)
{
struct node *ptr;
ptr = start;
while(ptr != NULL)
{
 printf(“\t %d”, ptr -> data);
 ptr = ptr -> next;
}
return start;
}
struct node *insert_beg(struct node *start)
{
struct node *new_node;
int num;
printf(“\n Enter the data : “);
scanf(“%d”, &num);
new_node = (struct node *)malloc(sizeof(struct node));
new_node -> data = num;
new_node -> next = start;
start = new_node;
return start;
}
struct node *insert_end(struct node *start)
{
struct node *ptr, *new_node;
int num;
printf(“\n Enter the data : “);
scanf(“%d”, &num);
new_node = (struct node *)malloc(sizeof(struct node));
new_node -> data = num;
new_node -> next = NULL;
ptr = start;
while(ptr -> next != NULL)
ptr = ptr -> next;
ptr -> next = new_node;
return start;
}
struct node *insert_before(struct node *start)
{
struct node *new_node, *ptr, *preptr;
int num, val;
printf(“\n Enter the data : “);
scanf(“%d”, &num);
printf(“\n Enter the value before which the data has to be inserted : “);
scanf(“%d”, &val);
new_node = (struct node *)malloc(sizeof(struct node));
new_node -> data = num;
ptr = start;
while(ptr -> data != val)
{
preptr = ptr;
 ptr = ptr -> next;
}
preptr -> next = new_node;
new_node -> next = ptr;
return start;
}
struct node *insert_after(struct node *start)
{
struct node *new_node, *ptr, *preptr;
int num, val;
printf(“\n Enter the data : “);
scanf(“%d”, &num);
printf(“\n Enter the value after which the data has to be inserted : “);
scanf(“%d”, &val);
new_node = (struct node *)malloc(sizeof(struct node));
new_node -> data = num;
ptr = start;
preptr = ptr;
while(preptr -> data != val)
{
 preptr = ptr;
 ptr = ptr -> next;
}
preptr -> next=new_node;
new_node -> next = ptr;
return start;
}
struct node *delete_beg(struct node *start)
{
struct node *ptr;
ptr = start;
start = start -> next;
free(ptr);
return start;
}
struct node *delete_end(struct node *start)
{
struct node *ptr, *preptr;
ptr = start;
while(ptr -> next != NULL)
{
 preptr = ptr;
 ptr = ptr -> next;
}
preptr -> next = NULL;
free(ptr);
return start;
}
struct node *delete_node(struct node *start)
{
struct node *ptr, *preptr;
int val;
printf(“\n Enter the value of the node which has to be deleted : “);
scanf(“%d”, &val);
ptr = start;
if(ptr -> data == val)
{
 start = delete_beg(start);
 return start;
}
else
{

while(ptr -> data != val)
 {
 preptr = ptr;
 ptr = ptr -> next;
 }
 preptr -> next = ptr -> next;
 free(ptr);
 return start;
}
}
struct node *delete_after(struct node *start) 
{
struct node *ptr, *preptr;
int val;
printf(“\n Enter the value after which the node has to deleted : “);
scanf(“%d”, &val);
ptr = start;
preptr = ptr;
while(preptr -> data != val)
{
 preptr = ptr;
 ptr = ptr -> next;
}
preptr -> next=ptr -> next;
free(ptr);
return start;
}
struct node *delete_list(struct node *start)
{
	 struct node *ptr; // Lines 252-254 were modified from original code to fix
unresposiveness in output window
if(start!=NULL){
 ptr=start;
 while(ptr != NULL)
 {
 printf(“\n %d is to be deleted next”, ptr -> data);
 start = delete_beg(ptr);
ptr = start;
 }
}
return start;
}
struct node *sort_list(struct node *start)
{
struct node *ptr1, *ptr2;
int temp;
ptr1 = start;
while(ptr1 -> next != NULL)
{
 ptr2 = ptr1 -> next;
 while(ptr2 != NULL)
 {
 if(ptr1 -> data > ptr2 -> data)
 {
 temp = ptr1 -> data;
 ptr1 -> data = ptr2 -> data;
 ptr2 -> data = temp;
 }
 ptr2 = ptr2 -> next;
 }
 ptr1 = ptr1 -> next;
}
return start; // Had to be added 
}