Question

You are off to shopping and need a program that allows you to enter the names of items, their price and quantities. Here is what a sample run should look like (with the keyboard input shown in italics) ...

    Enter item information ("exit" to exit)
    item 1: chips
    price: 3.5
    quantity: 2
    Enter item information ("exit" to exit)
    item 2: red wine
    price : 15.0
    quantity : 1
    Enter item information ("exit" to exit)
    item 3 : steaks
    price : 15.0
    quantity : 2
        
    Your list:
    steaks               2    $30
    red wine             1    $15
    chips                2    $7
    -----------------------------
    Total                     $52

You must ...

• Implement the program in C. (3.0%)
  • An array of structures must be used, so that each new item can be recorded in an element of the array.
  • It's not known in advance how many new items will be added to the list, so the program must malloc for an initial array of size 1, and use the doubling realloc technique (as discussed in class) to get more memory as required. You must always check the return value from malloc, as done in the Malloc wrapper function (or just use Malloc :-).
  • After you are done building the shopping list you must sort the array of structures according to the total price of each item.
  • Before the program completes it must explicitly free the malloced memory.

Answer 1

//--------- ShoppingCart.c --------------

#include<stdio.h>
#include<malloc.h>
#include<string.h>
typedef struct Item
{
   char name[100];
   float price;
   int quantity;
}Item;
Item* reAllocate(Item items[],int *size)
{
   int newSize = *size * 2;
   Item *newItems = (Item *) malloc(sizeof(Item) * newSize);
   int i = 0;
   for(i = 0;i<*size;i++)
   {
       strcpy(newItems[i].name,items[i].name);
       newItems[i].price = items[i].price;
       newItems[i].quantity = items[i].quantity;
   }
   *size = newSize;
   return newItems;
  
}
void copyItem(Item *target, Item src)
{
   strcpy(target->name , src.name);
   target->price = src.price;
   target->quantity = src.quantity;
}
void swapItem(Item *one,Item *two)
{
   Item temp;
   copyItem(&temp,*one);
   copyItem(one,*two);
   copyItem(two,temp);
  
}
void sortItems(Item items[], int size)
{
   int i,j;
   float totalOne,totalTwo;
   for(i = 0;i<size;i++)
   {
       for(j = 0;j<size-i-1;j++)
       {
           totalOne = items[j].price * items[j].quantity;
           totalTwo = items[j+1].price * items[j+1].quantity;
           if(totalOne <totalTwo)
           {
               swapItem(items+j,items+j+1);
           }
       }
   }
}
void printItems(Item items[], int size)
{
   int i;
   printf("\nYour List\n");
   float totalPrice = 0;
   float itemTotal = 0;
   for(i = 0;i<size;i++)
   {
       itemTotal = items[i].price*items[i].quantity;
       printf("\n%-20s %-10d %-10.2f\n",items[i].name,items[i].quantity,itemTotal);
       totalPrice += itemTotal;
   }
   printf("\n----------------------------------------\n");
   printf("Total %30.2f\n",totalPrice);
}
int main()
{
   int size = 1;
   Item* items = (Item *) malloc(sizeof(Item) * size);
   char name[100];
   float price;
   int quantity;
   char ch;
   int itemPos = 0;
   do
   {
       printf("\nEnter item Informaation (\"exit\" to exit)\n");
       printf("Item %d: ",itemPos+1);
       gets(name);
       if(strcmp(name,"exit") == 0)
       {
           break;
       }
       printf("price: ");
       scanf("%f",&price);
       if(price <0)
       {
           printf("\nError: Price cannot be negative");
           continue;
       }
       printf("quantity: ");
       scanf("%d",&quantity);
       scanf("%c",&ch);
       if(quantity <=0)
       {
           printf("\nError: Quantity cannot be negative or zero");
           continue;
       }
       strcpy(items[itemPos].name,name);
       items[itemPos].quantity = quantity;
       items[itemPos].price = price;
       itemPos++;
       if(itemPos == size)
       {
           items = reAllocate(items,&size);
       }
   }while(strcmp(name,"exit") != 0);
  
   sortItems(items,itemPos);
   printItems(items,itemPos);
   return 0;
}

//------------ OUTPUT -------------