The function insert of an ordered linked list class does not check for duplicate items before insertion. The document provides a solution to rewrite the insert function to check if the item to be inserted is already present in the list, and if so, output an error message without inserting. It includes the code for the modified insert function and a main function to test it by attempting to insert a duplicate item.

1. C++
7. The function insert of the class orderedLinkedList does not check if
the item to be inserted is already in the list; that is, it does not check for
duplicates. Rewrite the definition of the function insert so that before
inserting the item it checks whether the item to be inserted is already in the
list. If the item to be inserted is already in the list, the function outputs an
appropriate error message. Also write a program to test your function.
Solution
Code:
void Insert_in_sortedll(node* head, node* newnode)
{
node* curr;
if (head == NULL || head->data >= newnode->data)
{
if(head->data == newnode->data)//required checking condition
{
cout<<"item is already present";//error message printed
return ;
}
newnode->next = head;
head = newnode;
}
else
{
curr = head;
while (curr->next!=NULL && curr->next->data < newnode->data)
{
curr = curr->next;
}

2. if(curr->next&& curr->next->data == newnode->data)//required checking condition
{
cout<<"item is already present";//error message printed
return ;
}
newnode->next = curr->next;
curr->next = newnode;
}
}
using namespace std;
int main{
orderedLinkedList ll = new orderedLinkedList();
ll.Insert_in_sortedll(1);
ll.Insert_in_sortedll(1);//it should print error messsage
return 0;
}