Thread: Please help me troubleshoot this code

Hi guys I need your help. Basically this is a restaurant ordering program where a customer can ordering multiple kinds food in one order/transaction.

For example, i will input:
Table Number: 1
Priority Number: 1
How many kinds of food to order?: 2
Order 1: chicken
Quantity: 2
Order 2: salad
Quantity: 1

I am actually hoping that the program will output:

Code:

Table 1, Priority 0,
Order: chicken , Quantity: 2
Order: salad , Quantity: 1

But instead, it will just output:

Code:

Table 1, Priority 0,
Order: (null), Quantity: 2

So, here is the code:

Code:

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


typedef struct orders
{
    int *quantity[50];
    char *foodname[50];
}ORDER;


typedef struct Table
{
    int tableno;
    int priority;
    ORDER *orders;
    struct Table *next;
}TABLE;
TABLE *head, *s;


int n=0;


int insert(int tablenum, int prio, int kindsoforder, char *foodname[50], int qty[50])
{
    int l;
    TABLE *newO, *temp;
    newO = (TABLE *)malloc(sizeof(TABLE));
    newO->tableno = tablenum;
    newO->priority = prio;
    
    for(l=0;l<kindsoforder;l++)
    {
        strcpy(newO->orders->foodname[l], foodname[l]);
        newO->orders->quantity[l] = qty[l];
    }


    if(head == NULL)
    {
        head = newO;
        newO->next = NULL;
    }
    else
    {
        temp = head;
        newO->next = temp;
        while(temp->next != NULL)
        {
            if(newO->priority > head->priority)
            {
                head->next = newO;
                newO->next = temp->next;
            }
            else
            {
                newO->next = head->next;
                head->next = newO;
            }
            temp = temp->next;
        }
    }
    n++;
    printf("\nTotal numbers of orders for today: %d", n);
    return 1;
}


void showlist()    
{    
    int i, k;
    s=head;    
    for(i=0;i<n;i++)
    {
        printf("\nTable No: %d, Priority: %d,  \n",s->tableno, i);
        for(k=0;k<n;k++)
        {
            printf("Order: %s, Quantity: %d \n", s->orders->foodname[k],s->orders->quantity[k]);        
        }
        s=s->next;
    }
    printf("\n");
}




void main()
{
    int tablenum, prio, *qty[50], a, kindsoforder,j;
    char choice, *foodname[50];
    clrscr();
    while(choice != 'b')
    {
        flushall();
        printf("a. Order\nb. Exit\n");
        scanf("%c", &choice);


        switch(choice)        
        {
            case 'a':
                printf("Table Number: \n");
                scanf("%d", &tablenum);
                printf("Priority Number: \n");
                scanf("%d", &prio);
                printf("How many kinds of order? \n");
                scanf("%d", &kindsoforder);
                if(kindsoforder == 0)
                {
                    break;
                }
                else
                {
                    for(j=0;j<=kindsoforder;j++)
                    {
                        printf("Order %d: \n", j+1);
                        scanf("%s", &foodname[j]);
                        printf("Quantity? \n");
                        scanf("%d", &qty[j]);
                    }
                }
                a = insert(tablenum, prio, kindsoforder, foodname, qty);
                if (a == 1)
                {
                    printf("\nOrder inserted!\n\n");
                    showlist();
                }
                else
                {
                    printf("Order not inserted!\n");
                }


                
                break;
            case 'b':
                printf("Exit!");
                break;
        }
    }


getch();
}

Please help me.

Thanks for response

Originally Posted by Salem

When you've made these changes, then go through the rest of the code replacing -> with .

Done this but my compiler gives me an error, so I keep using ->.And also, I still have a problem. When I place on a new order, it prints out characters and symbols.

I just actually did what you said Salem. I just changed the pointer array into 2D array. Also, have you noticed that when you execute the program, for example, you have 2 kinds of food to order on your 1st order, but it will only display just one of your order.

And when you order another one, it now displays all the food you order on the first order. But for your 2nd order, it will display characters and symbols.

I am getting confused here. But i guess, we are coming close since it already prints the data on the struct.

I'm currently working on it right now. Hopefully, I could get it.

It's been 5 days and still I was not able to solve the problem. I have created a new code though. A bit similar to the previous, but only the user can now just order 1 name food every transaction. And it was set that if the next transaction has a higher priority, it will become the 1st priority. But, I still have a problem. I can't get it iterate through the linked list. Any help?

Anyway, here's the new code:

Code:

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


typedef struct orders
{
    int quantity;
    char foodname[50];
}ORDER;
ORDER *ptr;


typedef struct Table
{
    int tableno;
    int priority;
    ORDER *orders;
    struct Table *next;
}TABLE;
TABLE *head, *s;


int n=0;


int insert(int tablenum, int prio, char foodname[], int qty)
{
    TABLE *newO, *temp, *temp2;
    newO = (TABLE*)malloc(sizeof(TABLE));
    newO->tableno = tablenum;
    newO->priority = prio;
    strcpy(newO->orders->foodname, foodname);
    newO->orders->quantity = qty;


    if(head == NULL)
    {
        head = newO;
        newO->next = NULL;
    }
    else
    {
        temp = head;
        newO->next = temp;
        temp2->next = temp;


        while(temp2->next != NULL)
        {
            if(newO->priority > head->priority)
            {    
                head = newO;
                newO->next = temp->next;
            }
            else
            {
                newO->next = head->next;
                head->next = newO;
            }
            temp2 = temp2->next;
        }
    }
    n++;
    /*printf("%d", n);*/
    return 1;
}


void showlist()    //I think the problem is in this function. It wont display all data on the structure or iterate through the linked list.
{    
    int i;
    s=head;    
    for(i=1;i<=n;i++)
    {
        printf("\nPriority: %d, Table No: %d, Order: %s, Quantity: %d \n",i, s->tableno, s->orders->foodname,s->orders->quantity);        
        s=s->next;
    }
    printf("\n");
}


void main()
{
    int tablenum, prio, qty, a;
    char choice, foodname[50];
    clrscr();
    while(choice != 'b')
    {
        flushall();
        printf("a. Order\nb. Exit\n");
        scanf("%c", &choice);


        switch(choice)        
        {
            case 'a':
                printf("Table Number: \n");
                scanf("%d", &tablenum);
                printf("Priority Number: \n");
                scanf("%d", &prio);
                printf("What is your order? \n");
                scanf("%s", &foodname);
                printf("How many order? \n");
                scanf("%d", &qty);
                a = insert(tablenum, prio, foodname, qty);
                if (a == 1)
                {
                    printf("\nOrder inserted!\n\n");
                    showlist();
                }
                else
                {
                    printf("Order not inserted!\n");
                }


                
                break;
            case 'b':
                printf("Exit!");
                break;
        }
    }


getch();
}

Hello tabstop,

Those last two lines would be better if newO->orders pointed to something. Since it doesn't point to anything, your foodname and quantity disappear into the ether, never to be seen again. You need to create an ORDER for orders to point to, and then you can fill in the fields in that ORDER with foodname and quantity.

I think what you said is what I needed now. Can you show me an example on how this is usually done?

So, I get what you mean. I inserted the code below after line 30:

Code:

newO->orders = (ORDER*)malloc(sizeof(ORDER));

But now, I am having another problem. The first two transactions works well, but after I inputted the 3rd transaction, it just print out the data of the 3rd instruction again and again.

Your linked list is probably broken.

To insert a value at the front of a list it's:

Code:

new0->next = head;
head = new0;

Not the other way around. This makes it so 'head' is updated, and you can still use it.

I think you are trying to make it so the list is sorted by priority, but the way you are doing it now will also break the list. Inserting in the middle of a list means that the new value has to take on the next value of the previous node, because the new node is going to be placed after it. All you need to do for this snippet to work is search for and set prev. The snippet is:

Code:

new0->next = prev->next;
prev->next = new0;

This does not solve any problems if a user wants to update an existing table.