doubly linked list

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

struct linkedList
{
    int data;
    struct linkedList *next;
    struct linkedList *prev;
};
typedef struct linkedList *node;
node createnode()
{
    node temp;
    temp= (node)malloc(sizeof (struct linkedList));
    temp->next=NULL;
    temp->prev=NULL;
    return temp;
}
void print_node(node head)
{
    node p;
    p=head;
    while(p!=NULL)
    {
        printf("%d ", p->data);
        p=p->next;
    }
    printf("\n");
}
node add_node_front(node head, int data)
{
    node temp=createnode();
    temp->data=data;
    if(head==NULL)
    {
        head=temp;
        return head;
    }
    temp->prev=NULL;
    temp->next=head;
    head->prev=temp;
    head=temp;
    return head;
}
node add_node(node head,int value)
{
    node temp=createnode(),p;
    temp->data=value;
    if(head==NULL)
    {
        head=temp;
        return head;
    }
    p=head;
    while(p->next!=NULL)
    {
        p=p->next;
    }
    p->next=temp;
    temp->prev=p;
    return head;
}
node print_node_rev(node head)
{
    node p;
    if(head==NULL)
        printf("empty\n");
    else
    {
        p=head;
        while(p->next!=NULL)
        {
            p=p->next;
        }
        while(p->prev!=NULL)
        {
            printf("%d ",p->data);
            p=p->prev;
        }
        printf("%d ",p->data);
        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;

}
void delete_node(node head, int value)
{
    node p, n;
    if(head->data==NULL)
    {
        printf(" No element in List\n");
        return;
    }
    while(head->data!=value)
        head=head->next;
    if( head->prev!=NULL && head->next!=NULL )
    {
        p=head->prev;
        n=head->next;
        p->next=n;
        n->prev=p;
    }
    else if(head->prev==NULL && head->next!=NULL )
    {
        n=head->next;
        n->prev=NULL;
    }
    else if(head->prev!=NULL && head->next==NULL )
    {
        p=head->prev;
        p->next=NULL;
    }
    else if (head->prev==NULL && head->next==NULL)
        head->data=NULL;
    return;
}
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;

}
node insert_node_front(node head,int value1,int value2)
{
    node p=createnode(),q;
    p->data=value2;
    q=head;
    while(q->data!=value1)
        q=q->next;
    p->prev = q->prev;
    p->next = q;
    q->prev = p;
    if(p->prev!=NULL)
    {
        p->prev->next = p;
    }
    else
    {
        head = p;
    }

    return head;
}
int main()
{
    int n,data;
    node head=NULL;
    printf("1. add node at back\n2. add node at front\n3. print\n4. print reverse\n5. update node\n6. delete node\n7. insert a node (back)\n8. insert a node (front)\n0. exit\n");
    while(1)
    {
        scanf("%d",&n);
        if(n==2)
        {
            printf("new data : ");
            scanf("%d", &data);
            head=add_node_front(head,data);
        }
        else if(n==1)
        {
            printf("new data : ");
            scanf("%d", &data);
            head=add_node(head,data);
        }
        else if(n==3)
        {
            print_node(head);
        }
        else if(n==4)
        {
            print_node_rev(head);
        }
        else if(n==5)
        {
            int x,y;
            scanf("%d %d",&x,&y);
            update_node(x,y,head);
        }
        else if(n==6)
        {
            int x;
            scanf("%d",&x);
            delete_node(head,x);
        }
        else if(n==7)
        {
            int x,y;
            scanf("%d %d",&x,&y);
            head=insert_node(head,x,y);
        }
        else if(n==8)
        {
            int a,b;
            scanf("%d %d",&a,&b);
            head=insert_node_front(head,a,b);
        }
        else if(n==0)
            return 0;
    }
}