Cart design
- C++ course
- Beginner
- Lesson 48/116
- 6 min
Design the struct and vector for the shopping cart.
Cart design
In this project we will build a shopping cart application step by step. The first step is to design the Product structure that represents an item in the cart. In C++ you use a struct to group related fields under one roof.
A product has three core fields: name (std::string), price (double) and quantity (int). Writing struct Product { std::string name; double price; int quantity; }; brings these three together. You will see more about struct in a later level; here we use it just to group data.
struct syntax
A struct is a data type that holds several variables. Its form is struct Name { type field1; type field2; };; the semicolon after the closing brace is mandatory.
To use a struct you first declare a variable, then access its fields with a dot: Product p; p.name = "Notebook"; p.price = 25.0; p.quantity = 2;. This way the three related pieces travel together and can be passed to a function as a single parameter.
Practice Define the Product struct
Define a struct Product with the fields std::string name, double price and int quantity. main already creates a product and prints its name; you only need to define the struct. The output must be Notebook.
Starter code
#include <iostream>
#include <string>
// Write the Product struct here
int main() {
Product p;
p.name = "Notebook";
p.price = 25.0;
p.quantity = 2;
std::cout << p.name << std::endl;
return 0;
}Sample solution
#include <iostream>
#include <string>
struct Product {
std::string name;
double price;
int quantity;
};
int main() {
Product p;
p.name = "Notebook";
p.price = 25.0;
p.quantity = 2;
std::cout << p.name << std::endl;
return 0;
}Expected output
Notebook
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which type fits the product name in the Product struct?
struct Product { ... name ...; };- std::string Correct answer
- int
- double
- bool
Explanation: Text is held in std::string.
2 Write the struct name
struct ____ {
std::string name;
double price;
int quantity;
};struct Product {
std::string name;
double price;
int quantity;
};Explanation: The struct is named Product and starts with a capital letter.
3 Match each field to its type
| Term | Meaning |
|---|---|
name |
std::string |
price |
double |
quantity |
int |
items |
std::vector<Product> |