another bs

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <malloc.h>
#include <string.h>
struct node {
	struct node *next;
	char name[30];
	char brand[5];
	char type[20];
	char damage[20];
	struct node *prev;
};

void clrscr() {
	system("@cls||clear");
}


struct node *start = NULL;
struct node *create_ll(struct node *);
struct node *display(struct node *);
struct node *insert_end(struct node *);
struct node *delete_beg(struct node *);

int main(int argc, char *argv[]) {
    int choice;
    do {
    	clrscr();
		printf("PRINTER SERVICES\n");
		printf("++++++++++++++++++++++\n\n");
		printf("1. Service List\n");
		printf("2. Add Service\n");
		printf("3. Take Service\n");
		printf("4. Exit\n\n");
		printf("> Please input your choice : ");
        scanf("%d", &choice);
        switch(choice) {
            case 1: {
            	start = display(start);
            	getch();
				break;
			}
            break;
            case 2: {
            	start = create_ll(start);
            	getch();
				break;
			}
            break;
            case 3: {
            	start = delete_beg(start);
            	getch();
				break;
			}
			case 4: break;
        }
    } while(choice !=5);
    getch();
    return 0;
}
struct node *create_ll(struct node *start) {
	struct node *new_node, *ptr;

	char name[25],brand[5],type[20],damage[20];
	int b=0;
	printf("\nInput Customer Name : ");
	fflush(stdin);
	scanf("%[^\n]",&name);
	do{
		 printf("Input Printer's Brand [canon/epson/hp] : ");
		 scanf("%s",&brand);
	   	if (strcmp("canon",brand)==0) {
			b=1;
		}
		else if (strcmp("epson",brand)==0) {
			b=1;
		}
		else if (strcmp("hp",brand)==0) {
			b=1;
		}
		else {
			b=0;
		}

	} while (b==0);

	do {
		 printf("Input Printer's Type [4...20]: ");
		 scanf("%s",&type);
	} while (strlen(type)<4 || strlen(type)>20);

	do {
		 printf("Input Damaged [5...20]: ");
		 fflush(stdin);
		 scanf("%[^\n]",&damage);
	} while (strlen(damage)<5 || strlen(damage)>20);

	new_node = (struct node*)malloc(sizeof(struct node));
	strcpy(new_node->name,name);
	strcpy(new_node->brand,brand);
	strcpy(new_node->type,type);
	strcpy(new_node->damage,damage);
	if(start == NULL) {
		new_node->next = NULL;
		start = new_node;
	}
	else {
		ptr=start;
		while(ptr->next!=NULL) {
			ptr=ptr->next;
		}
		ptr->next = new_node;
		new_node->next=NULL;
	}
	return start;
}

struct node *display(struct node *start) {
	int no=1;
	struct node *ptr;
	ptr=start;
	clrscr();
	printf("\nP R I N T E R   S E R V I C E S\n===============================\n\n");
	printf("---------------------------------------------------------------------------------------------------------\n");
	printf("| No.   |  name          \t\t|Printer's Brand    |    Type             |   \t Damaged        |\n");
	printf("---------------------------------------------------------------------------------------------------------\n");
	while (ptr!=NULL) {
		printf("|");
		printf("%-6d |",no);
		printf("%-30s |",ptr->name);
		printf("%-18s |",ptr->brand);
		printf("%-20s |",ptr->type);
		printf("%-20s |\n",ptr->damage);
		ptr=ptr->next;
		no++;
	}
	return start;
}
struct node *delete_beg(struct node *start) {
	struct node *ptr;
	ptr = start;
	start = start -> next;
	start -> prev = NULL;
	free(ptr);
	return start;
}