Structure Functions

**trprince** · 12-12-2007

I am writing a function that compares two structures. It compares the names and the quantity. The total cost is then the price times the quantity wanted. if the the item is not there then there is a printed error and if the quantity exceeds the available quanitity then prints an error message. if the the item name is there and the item quantity is available, then it prints the item, the quanitity, and the price. My outoput looks like this

There are 4 items in inventory.
There are 3 items in grocery list
Item: potatoes
does not exist
Item: 2-liter soda
does not exist
Item: pounds of hamburger does not exist
Item: done
does not exist
------------------------------
Total Cost: $0.00

This is my code:

Code:

typedef struct{   
    char name[STRINGMAX];
    int quantity; 
}Grocery_List_Item; 

typedef struct{
      char name[STRINGMAX];
      int quantity;
      float price;
} InvItem;

typedef InvItem InvArr[ITEMMAX];    
typedef Grocery_List_Item Grocery_Arr[ITEMMAX];   

int availability(Grocery_Arr groc_list, InvArr inv_list); 
int fill_grocery_list(Grocery_Arr groc_list); 
int fill_inv(InvArr inv_list); 
void empty_str(char name[]); 
 
int main(){ 
  InvArr inv_item; 
  Grocery_Arr want_item; 
  int num_InvItems, num_GrocItems; 
 
  num_InvItems = fill_inv(inv_item); 
  num_GrocItems = fill_grocery_list(want_item); 
  printf("There are &#37;d items in inventory.\n",num_InvItems); 
  printf("There are %d items in the grocery list.\n",num_GrocItems); 
  printf("Purchasing:\n"); 
  availability(want_item, inv_item); 
 
  return 0; 
} 
 
 
void empty_str(char name[]){ 
  char *last = strrchr(name,'\n'); 
  if(last != NULL) 
    *last = '\0'; 
}

int fill_inv(InvArr inv_list){ 
  int count = 0; 
  char temparr[STRINGMAX + 1]; 
  do{ 
    scanf("%f", &inv_list[count].price); 
    scanf("%d", &inv_list[count].quantity); 
    fgets(temparr, STRINGMAX, stdin); 
    strcpy(inv_list[count].name, temparr); 
    empty_str(temparr); 
  }while(inv_list[count++].price !=0); 
 
  return (count - 2); 
} 
 
int fill_grocery_list(Grocery_Arr groc_list){ 
  int count = 0; 
  char temparr[STRINGMAX + 1]; 
  do{ 
    scanf("%d",&groc_list[count].quantity); 
    fgets(temparr, STRINGMAX + 1, stdin); 
    strcpy(groc_list[count].name, temparr); 
    empty_str(temparr); 
  }while(groc_list[count++].quantity !=0); 
 
  return (count - 1); 
}

int availability(Grocery_Arr groc_list, InvArr inv_list){ 
  int match, count = 0; 
  float total = 0.0, new_price = 0; 
  do{ 
    match = strcmp(groc_list[count].name, inv_list[count].name); 
    if((match == 0) && (groc_list[count].quantity <= inv_list[count].quantity)){ 
      new_price += (groc_list[count].quantity * inv_list[count].price); 
      printf("%s %d $%f\n",groc_list[count].name,groc_list[count].quantity,new_price); 
      total += new_price; 
    } 
    else if((match == 0) && (groc_list[count].quantity > inv_list[count].quantity)) 
      printf("Item: %s insufficient quantity\n",groc_list[count].name); 
    else 
      printf("Item: %s does not exist\n",groc_list[count].name); 
  }while(groc_list[count++].quantity !=0); 
  printf("-------------------------\n"); 
  printf("Total Cost: $ %.2f\n",total); 
  return total; 
}

**vart** · 12-12-2007

You forgot to add your question.

**trprince** · 12-12-2007

oksy so now I have two problems. The last sentinel (done 0) is printing and i don't want that because its my sentinel. And also the big problem is that my numbers new_price is multiplying wrong. I know it's not multiplying by the correct price that matches the name of the item. Can you help me fix that? Please

output:

There are 4 items in inventory.
There are 3 items in the grocery list.
Purchasing:
potatoes 5 $12.45
2-liter soda 3 $0.93
pounds of hamburger 2 $2.50
done 0 $0.00
-------------------------
Total Cost: $ 15.88

Code:

int fill_inv(InvArr inv_list){ 
  int count = 0; 
  char temparr[STRINGMAX+2];
  do{ 
    scanf("%f %d", &inv_list[count].price, &inv_list[count].quantity);
    fgets(temparr, STRINGMAX+2, stdin);
    strncpy(inv_list[count].name, temparr, STRINGMAX);
    inv_list[count].name[STRINGMAX+1]='\0';
    empty_str(temparr); 
  }while(inv_list[count++].price !=0); 
 
  return (count - 1); 
} 

int fill_grocery_list(Grocery_Arr groc_list){
  int count = 0;
  char temparr[STRINGMAX+2];
  do{
    scanf("%d",&groc_list[count].quantity);
    fgets(temparr, STRINGMAX+2, stdin);
    empty_str(temparr);
    strncpy(groc_list[count].name, temparr, STRINGMAX);
    groc_list[count].name[STRINGMAX+1] = '\0';
  }while(groc_list[count++].quantity != 0);
 
  return (count - 1); 
} 
 
 
int availability(Grocery_Arr groc_list, InvArr inv_list){ 
  int match, count = 0; 
  float total = 0.0, new_price; 
  do{ 
    match = strcmp(groc_list[count].name, inv_list[count].name); 
    if((match) && (groc_list[count].quantity <= inv_list[count].quantity)){ 
      new_price = ((float)groc_list[count].quantity * inv_list[count].price); 
      printf("%s %d $%.2f\n", groc_list[count].name, groc_list[count].quantity, new_price); 
      total += new_price; 
    } 
    else if((match) && (groc_list[count].quantity > inv_list[count].quantity)) 
      printf("Item: %s insufficient quantity\n",groc_list[count].name); 
    else 
      printf("Item: %s does not exist\n",groc_list[count].name); 
  }while(groc_list[count++].quantity !=0); 
  printf("-------------------------\n"); 
  printf("Total Cost: $ %.2f\n",total); 
  return total; 
}

**vart** · 12-12-2007

1. The last sentinel (done 0) is printing and i don't want that because its my sentinel
I see 2 possibilitie
- do not add this item to the list (requires more changes
- do not print it - small fix needed:
in the function availability replace the do/while(); loop with the while loop keeping the condition

2. Why do you think that new price is multiplied wrong? Provide the input data, expected result for 1 Item and received result

**trprince** · 12-12-2007

So just make it a plain while loop?

It's multiplying by the first one then the second one and so on.

::::::::::::::
in1
::::::::::::::
2.49 9 pounds of hamburger
.31 20 potatoes
1.25 12 vitamin water
.89 8 2-liter soda
0 0 done
5 potatoes
3 2-liter soda
2 pounds of hamburger
0 done
::::::::::::::
out1
::::::::::::::
There are 4 items in inventory.
Purchasing:
potatoes 5 $1.55
2-liter soda 3 $2.67
pounds of hamburger 2 $4.98
---------------------
Total Cost: $9.20

**vart** · 12-12-2007

match = strcmp - strcmp returns 0 for matched strings - check your condition on match

**trprince** · 12-12-2007

what do you mean check the condition. If it does =0 then do the following statements. Should I chagne it?

**vart** · 12-13-2007

if((match) - it is true when string do not match.

Change the variable name or how you assign a value, so that the value will be consistent with the name

**trprince** · 12-13-2007

even when i change the name, I'm still gettting the same thing. I don't really understand.

**tabstop** · 12-13-2007

You assign match to be the result of a strcmp. But if the strings match, strcmp returns 0 -- which means if (match) does the opposite of what you think/want it to do (since match, interpreted as true/false, will give false when they match and true when they don't).

So the suggestion was to change the variable name to something like not_match, then in your if you can do if (!(not_match) && ....)

EDIT: Or, you had it right the first time, looking back. If (match==0 ...)

**Elysia** · 12-13-2007

Better yet, define it something like a bool and so

Code:

match = (strcmp(groc_list[count].name, inv_list[count].name) == 0);

Will save true if strcmp returned 0 (which it does if strings match) or false if they did not match (strcmp returned something other than 0).

**trprince** · 12-13-2007

ok...so when i do the

Code:

match = (strcmp(groc_list[count].name, inv_list[count].name) == 0);

i get this output

There are 4 items in inventory.
There are 3 items in the grocery list.
Purchasing:
Item: potatoes does not exist
Item: 2-liter soda does not exist
Item: pounds of hamburger^B does not exist
Item: done does not exist
-------------------------
Total Cost: $ 0.00

**trprince** · 12-13-2007

it doesn't even read them...i'm so out of ideas

**trprince** · 12-13-2007

ok so now my functon is this

Code:

int availability(Grocery_Arr groc_list, InvArr inv_list, int num_items){ 
   int count;  
   float total = 0.0, new_price;  
   for(count = 0; count < num_items; count++){   
     if((strcmp(groc_list[count].name, inv_list[count].name)) != 0){  /*COMPARE THE NAMES OF THE ITEMS*/ 
        if(groc_list[count].quantity <= inv_list[count].quantity){   /*IF AVAILABLE FOR PURCHASE*/ 
           new_price = ((float)groc_list[count].quantity * inv_list[count].price);   /*CALCULATE NEW PRICE*/
           printf("%s %d $%.2f\n", groc_list[count].name, groc_list[count].quantity, new_price);
           total += new_price;   /*CALCULATE NEW TOTAL*/ 
        }
        else if(groc_list[count].quantity > inv_list[count].quantity)  /*IF AVAILABLE BUT NOT RIGHT QUANTITY*/ 
           printf("Item: %s insufficient quantity\n",groc_list[count].name);  
     }     
else  
    printf("Item: %s does not exist\n",groc_list[count].name);  /*IF ITEM DOES NOT EXIST*/
   } 
   printf("-------------------------\n");
   printf("Total Cost: $ %.2f\n",total);   
   return total; 
}

with an output of

There are 4 items in inventory.
There are 3 items in the grocery list.
Purchasing:
potatoes 5 $12.45
2-liter soda 3 $0.93
pounds of hamburger 2 $2.50
-------------------------
Total Cost: $ 15.88

**tabstop** · 12-13-2007

You're using the same index for the groc_list and the inv_list, which is why the first item bought always costs $2.49, the second costs $0.31, the third costs $1.25, etc.

You need to loop through the grocery list, and inside that loop loop through the inventory. You'll need max_items for both lists, though, it looks like.

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