sem 2 linked list lab 5

#include<stdio.h>
#include<stdlib.h>
struct linked_list
{
    int data;
    struct linked_list *next;
};
typedef struct linked_list *node;

node createnode()
{
    node temp;
    temp=(node)malloc(sizeof(node));
    temp->next=NULL;
    return temp;
}
node add_node(node head,int value)
{
    node temp=createnode(),p;
    temp->data=value;
    if(head==NULL)
        head=temp;
    else
    {
        p=head;
        while(p->next!=NULL)
            p=p->next;
        p->next=temp;
    }
    return head;
}
void print_node(node head)
{
    node a;
    if(head==NULL)
        printf("empty\n");
    else
    {
        a=head;
        while(a!=NULL)
        {
            printf("%d ",a->data);
            a=a->next;
        }
    }
    printf("\n");
}
node update_node(int value1,int value2,node head)
{
    node p;
    p=head;
    while(p->data!=value1)
        p=p->next;
    if(p==NULL)
        printf("%d is not in the list\n",value1);
    else
        p->data=value2;

    return head;

}
node delete_node(node head,int value)
{
    node p=head,prev;
    if(p!=NULL&&p->data==value)
    {
        head=p->next;
        free(p);
        return head;
    }
    while(p!=NULL&&p->data!=value)
    {
        prev=p;
        p=p->next;
    }

    if(p==NULL)
        printf("%d is not in the list\n",value);
    else
    {
        prev->next=p->next;
        free(p);
    }
    return head;
}
node insert_node(node head,int value1,int value2)
{
    node p=createnode(),q;
    p->data=value2;
    q=head;
    while(q->data!=value1)
        q=q->next;
    if(q==NULL)
        printf("%d is not in the list\n",value1);
    else
    {
        p->next=q->next;
        q->next=p;
    }
    return head;

}
int main()
{
    printf("enter 1 to add node at the end\nenter 2 to print\nenter 3 to update node\nenter 4 to delete\nenter 5 to insert\nenter 0 to exit\n");
    int n;
    node head;
    head=NULL;
    while(1)
    {
        scanf("%d",&n);
        if(n==1)
        {
            int ndata;
            printf("new data ");
            scanf("%d",&ndata);
            head=add_node(head,ndata);
        }
        else if(n==2)
        {
            print_node(head);
        }
        else if(n==3)
        {
            int x,y;
            scanf("%d %d",&x,&y);
            update_node(x,y,head);
        }
        else if(n==4)
        {
            int x;
            scanf("%d",&x);
            head=delete_node(head,x);
        }
        else if(n==5)
        {
            int x,y;
            scanf("%d %d",&x,&y);
            head=insert_node(head,x,y);
        }
        else if(n==0)
            return 0;
    }
}