hore doubly nya jalan

#include<stdlib.h>
#include<stdio.h>
#include<conio.h>
#include<malloc.h>

struct cust{
	char name[20];
	char city[20];
	int numb;
	char addr[30];
	struct cust *next;
	struct cust *prev;
};

cust *start=NULL, *ptr;

void menu() {
	printf("DATABASE CUSTOMER\n");
	printf(". . . . . . . . .\n\n");
	printf("1. View customer database\n");
	printf("2. Add new customer\n");
	printf("3. Exit\n");
	printf("\n> Please input your choice : ");
}

void add(struct cust** head_ref, int new_data) {
	int nnumb;
	char nama, alamat, kota;
	struct cust* new_node = (struct cust*)malloc(sizeof(struct cust));
	struct cust* tail = *head_ref;
	printf("Input company name [5..30] : ");
	scanf("%s", &nama);
	printf("Input address [5..50] : ");
	scanf("%s", &alamat);
	printf("Input city [5..30] : ");
	scanf("%s", &kota);
	printf("Input phone number : ");
	scanf("%d", &nnumb);

	new_node->numb = new_data;
	new_node->next = NULL;
	if (ptr == NULL) {
		new_node->prev = NULL;
		*head_ref = new_node;
		return;
	}
	while (tail->next != NULL)
		tail = tail->next;
	tail->next = new_node;
	new_node->prev = tail;
	return;
}


int main() {
	int input;
	struct cust* head = NULL;
	add(&head, input);
}