tulung saya pusink

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

void clrscr(){
	system("@cls||clear");
}
struct node{
	char name[20];
	int qty;
	int price;
	struct node *next;
};

struct node *start=NULL;
struct node *print(struct node*);
struct node *add_node(struct node*);
struct node *pop(struct node*);

int count=0,i;

int main(){
	int loop=1;
	do{
		clrscr();
		printf("BLUE MOTORCYCLE PARTS\n");
		printf(".....................\n\n");
		printf("1. View order list\n");
		printf("2. Add new order\n");
		printf("3. Take order\n");
		printf("4. Exit\n\n");
		int choice;
		do{
			printf("> Please choose menu : ");
			scanf("%d",&choice);
		}while(choice<1||choice>4);
		switch(choice){
			case 1:{
				clrscr();
				start=print(start);
				getch();
				break;
			}
			case 2:{
				clrscr();
				start=add_node(start);
				getch();
				break;
			}
			case 3:{
				clrscr();
				start=print(start);
				start=pop(start);
				getch();
				break;
			}
			case 4:{
				for(;count>0;count--){
					struct node *ptr;
					ptr=start;
					while(ptr->next!=start){
						ptr=ptr->next;
					}
					ptr->next=start->next;
					free(start);
					start=ptr->next;
				}
				loop=0;
				break;
			}
		}
	}while(loop==1);
	printf("Thank You");
	return 0;
}

struct node *print(struct node *n){
	printf("                   --- ITEM LIST---\n\n");
	printf("------+----------------------+--------------+----------------\n");
	printf("| No. | Name of Parts        | Quantity     | Price         |\n");
	printf("------+----------------------+--------------+----------------\n");
	if(count>0){
		int i=1;
		struct node *ptr;
		ptr=n;
		if(count>1){
			printf("| %2d. | %20s | %12d | %13d |    << Head\n",i,ptr->name,ptr->qty,ptr->price);
			ptr=ptr->next;
			i++;
		}
		while(ptr->next!=n){
			printf("| %2d. | %20s | %12d | %13d |\n",i,ptr->name,ptr->qty,ptr->price);
			ptr=ptr->next;
			i++;
		}
		if(count==1){
			printf("| %2d. | %20s | %12d | %13d |    << Head Tail\n",i,ptr->name,ptr->qty,ptr->price);
		}else{
			printf("| %2d. | %20s | %12d | %13d |    << Tail\n",i,ptr->name,ptr->qty,ptr->price);
		}
	}
	printf("------+----------------------+--------------+----------------\n");
	return n;
}

struct node *add_node(struct node *start){
	struct node *new_node,*ptr;
	int pprice, qqty;
	char nname[31];
	do{
		printf("Input name of motorcycle's part [3..20]: ");
		fflush(stdin);
		scanf("%s",nname);
		}
	}while(strlen(nname)<3||strlen(nname)>30);

	do{
		printf("Input quantity of the motorcycle's Part [1..20]: ");
		scanf("%d",&qqty);
	}while(qqty<1||qqty>20);

	do{
		printf("Input price of the motorcycle's part : ");
		scanf("%d",&pprice);
	}while(pprice<1);

	new_node=(struct node*)malloc(sizeof(struct node));
	strcpy(new_node->name,nname);
	new_node->qty=qqty;
	new_node->price=pprice;

	if(start==NULL){
		start=new_node;
		start->next=start;
	}else{
		ptr=start;
		while(ptr->next!=start){
			ptr=ptr->next;
		}
		ptr->next=new_node;
		new_node->next=start;
	}

	count++;
	printf("--- Add new node success ---");
	return start;

}

struct node *pop(struct node *start){
	struct node *ptr;
	if(pil==0){
		printf("There are no node available.");
	}
	else{
		struct node *ptr,*temp;
		ptr=start;
		int input;
		do{
			printf("Input number of the order [1..%d] : ",pil);
			scanf("%d",&input);
		}while(input<1||input>pil);
		if(input>1){
			for(i=1;i<(input-1);i++){
				ptr=ptr->next;
			}
			temp=ptr->next;
			ptr->next=temp->next;
			free(temp);
		}
		else{
			while(ptr->next!=start){
				ptr=ptr->next;
			}
			ptr->next=start->next;
			temp=start;
			start=ptr->next;
			free(temp);
		}
		printf("--- Take order success ---\n");
		pil--;
	}
	return start;
}