given node

//INSERT SPECIFIC
/**** Program to Insert at Specific Node in a Linked List ****/
#include <stdio.h>
#include<malloc.h>
#include<iostream>
using namespace std;
void insert_last();
void insert_specific();
void display();
struct node
{
int info;
struct node *link;
} *start=NULL;
int item;

int main()
{
int ch;
do
{
printf("\n\n\n1. Insert Last\n2. Insert Specific\n3. Display\n4.Exit\n");
printf("\nEnter your choice: ");
scanf("%d", &ch);
switch(ch)
{
case 1:
insert_last();
break;
case 2:
insert_specific();
break;
case 3:
display();
break;
case 4:
return 0;
default:
printf("\n\nInvalid choice. Please try again.\n");
}
} while (1);
}


void insert_last()
{
struct node *ptr;
printf("\n\nEnter item: ");
scanf("%d", &item);
if(start == NULL)
{
start = (struct node *)malloc(sizeof(struct node));
start->info = item;
start->link = NULL;
}
else
{
ptr = start;
while (ptr->link != NULL)
ptr = ptr->link;
ptr->link = (struct node *)malloc(sizeof(struct node));
ptr = ptr->link;
ptr->info = item;
ptr->link = NULL;
}
printf("\nItem inserted: %d\n", item);
}

void insert_specific()
{
int n;
struct node *newn, *ptr;
if (start == NULL)
printf("\n\nLinked list is empty. It must have at least onenode.\n");
else
{
printf("\n\nEnter INFO after which new node is to be inserted: ");
scanf("%d", &n);
printf("\n\nEnter ITEM: ");
scanf("%d", &item);
ptr = start;
newn = start;

while (ptr != NULL)
{
if (ptr->info == n)
{
newn = (struct node *)malloc(sizeof(struct node));
newn->info = item;
newn->link = ptr->link;
ptr->link = newn;
printf("\n\nItem inserted: %d", item);
return;
}
else
ptr = ptr->link;
}
}
}

void display()
{
struct node *ptr = start;
int i=1;
if (ptr != NULL)
{

	while(ptr != NULL)
{

printf("\n Sr. No.\tAddress\t\tInfo\t\tLink\n\n%d.\t\t%d\t\t%d\t\t%d\n", i, ptr, ptr->info,ptr->link);
ptr = ptr->link;
i++;
}
}
else
{
printf("\nLinklist is empty.\n");

}
}