C++ Playground

A starter program to experiment with. Edit it here, press Copy, paste it into a file called main.cpp, and compile and run it with c++ -std=c++20 -Wall -Wextra main.cpp -o main && ./main. Lesson 2 shows how to install a compiler.

#include <algorithm>
#include <format>
#include <iostream>
#include <string>
#include <vector>

struct Item {
    std::string name;
    double price;
    int quantity;
    double total() const { return price * quantity; }
};

int main() {
    std::vector<Item> basket{
        {"Notebook", 3.50, 4},
        {"Pen", 1.20, 10},
        {"Backpack", 39.90, 1},
    };

    std::ranges::sort(basket, std::greater{}, &Item::total);   // most expensive line first

    double sum = 0;
    for (const auto& item : basket) {
        std::cout << std::format("{:<10} {:>3} x {:>6.2f} = {:>7.2f}\n",
                                 item.name, item.quantity, item.price, item.total());
        sum += item.total();
    }
    std::cout << std::format("Total: {:.2f}\n", sum);
}

Edit the code, copy it into main.cpp, then compile and run it with c++ -std=c++20 -Wall main.cpp -o main && ./main. How to set up a C++ compiler

Output

Backpack     1 x  39.90 =   39.90
Notebook     4 x   3.50 =   14.00
Pen         10 x   1.20 =   12.00
Total: 65.90

Ideas to try

Apply a 10% discount when the total is over 50 (lesson 10).
Read the items from a file instead of hard-coding them (lesson 44).
Count items under 5.00 with std::ranges::count_if and a lambda (lessons 24–25).
Turn Item into a class that rejects negative prices in its constructor (lesson 32).
Print with C++23's std::println instead of std::cout (lesson 50).

Compiling without installing anything

Online compilers such as Compiler Explorer (godbolt.org) compile and run C++ in your browser. Choose a recent GCC or Clang and add -std=c++20 to the compiler options.

PreviousProject: Library Catalogue NextExercises