Listing the cart
- C course
- Beginner
- Lesson 51/116
- 6 min
Write the function that prints the cart items formatted.
The cart_list function
In this lesson we'll write the cart_list function. It prints all cart items in a formatted way.
void cart_list(void) {
for (int i = 0; i < cart_size; i++) {
printf("%s %.2f x %d = %.2f\n",
cart[i].name, cart[i].price, cart[i].qty,
cart[i].price * cart[i].qty);
}
}Each line shows an item: name, price, quantity and subtotal. This output tells the user what's in the cart. We iterate with for and print each line.
Formatted output
When printing money values, using %.2f is a good habit; it shows two decimal digits. Currencies usually have two digits.
printf("%s %.2f x %d = %.2f\n",
"Apple", 2.50, 3, 7.50);
// Output: Apple 2.50 x 3 = 7.50Here %s is name, %.2f is price, %d is quantity and the last %.2f is subtotal. Specifier order must match variable order.
Practice List the cart
Write the cart_list function: void cart_list(void). With for (int i = 0; i < cart_size; i++) print each item using printf("%s %.2f x %d = %.2f\n", cart[i].name, cart[i].price, cart[i].qty, cart[i].price * cart[i].qty);. main already calls cart_list(); just complete the function. Expected output: Apple 2.50 x 3 = 7.50 / Bread 5.00 x 1 = 5.00.
Starter code
#include <stdio.h>
#include <string.h>
#define MAX_ITEMS 10
struct CartItem {
char name[32];
double price;
int qty;
};
struct CartItem cart[MAX_ITEMS];
int cart_size = 0;
void cart_add(const char *name, double price, int qty) {
if (cart_size >= MAX_ITEMS) return;
strcpy(cart[cart_size].name, name);
cart[cart_size].price = price;
cart[cart_size].qty = qty;
cart_size++;
}
double cart_subtotal(void) {
double sum = 0;
for (int i = 0; i < cart_size; i++) {
sum += cart[i].price * cart[i].qty;
}
return sum;
}
// Write the cart_list function here
int main(void) {
cart_add("Apple", 2.50, 3);
cart_add("Bread", 5.00, 1);
cart_list();
return 0;
}Sample solution
#include <stdio.h>
#include <string.h>
#define MAX_ITEMS 10
struct CartItem {
char name[32];
double price;
int qty;
};
struct CartItem cart[MAX_ITEMS];
int cart_size = 0;
void cart_add(const char *name, double price, int qty) {
if (cart_size >= MAX_ITEMS) return;
strcpy(cart[cart_size].name, name);
cart[cart_size].price = price;
cart[cart_size].qty = qty;
cart_size++;
}
double cart_subtotal(void) {
double sum = 0;
for (int i = 0; i < cart_size; i++) {
sum += cart[i].price * cart[i].qty;
}
return sum;
}
void cart_list(void) {
for (int i = 0; i < cart_size; i++) {
printf("%s %.2f x %d = %.2f\n", cart[i].name, cart[i].price, cart[i].qty, cart[i].price * cart[i].qty);
}
}
int main(void) {
cart_add("Apple", 2.50, 3);
cart_add("Bread", 5.00, 1);
cart_list();
return 0;
}Expected output
Apple 2.50 x 3 = 7.50 Bread 5.00 x 1 = 5.00
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Match the list pieces
| Term | Meaning |
|---|---|
%s |
Name |
%.2f |
Price |
%d |
Quantity |
price * qty |
Subtotal |
2 What does cart_list print?
void cart_list(void) {
for (...) {
printf("%s %.2f x %d", ...);
}
}- Only the name
- Only the price
- Only the quantity
- Name, price, quantity and subtotal Correct answer
Explanation: cart_list prints all information of each item.
3 Print the item name
printf("____ %.2f x %d = %.2f
", cart[i].name, cart[i].price, cart[i].qty, cart[i].price * cart[i].qty);printf("%s %.2f x %d = %.2f
", cart[i].name, cart[i].price, cart[i].qty, cart[i].price * cart[i].qty);Explanation: %s is used for strings (the item name).