Go Playground

A starter program to experiment with. Edit it here, press Copy, paste it into a file called main.go, and run it with go run main.go. Lesson 2 shows how to install Go.

package main

import (
	"cmp"
	"fmt"
	"slices"
)

type Item struct {
	Name     string
	Price    float64
	Quantity int
}

func (i Item) Total() float64 {
	return i.Price * float64(i.Quantity)
}

func main() {
	basket := []Item{
		{"Notebook", 3.50, 4},
		{"Pen", 1.20, 10},
		{"Backpack", 39.90, 1},
	}

	slices.SortFunc(basket, func(a, b Item) int {
		return cmp.Compare(b.Total(), a.Total()) // most expensive line first
	})

	sum := 0.0
	for _, it := range basket {
		fmt.Printf("%-10s %3d x %6.2f = %7.2f\n", it.Name, it.Quantity, it.Price, it.Total())
		sum += it.Total()
	}
	fmt.Printf("Total: %.2f\n", sum)
}

Edit the code, copy it into main.go in a new folder and run it with go run main.go (Go 1.27 or later). How to install Go

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 14).
Read the items from a CSV file with bufio.Scanner and strings.Split (lesson 57).
Group items into "cheap" and "expensive" with a map of slices (lesson 28).
Add a NewItem constructor that returns an error for negative prices (lessons 36 and 44).
Give Item a String method so fmt.Println(it) prints a tidy line (lesson 42).
Serve the basket as JSON from an HTTP endpoint (lessons 59 and 61).

Running Go without installing anything

The Go Playground at go.dev/play compiles and runs programs in your browser and lets you share them by link. It's great for quick experiments; for files, input and servers you'll want a local installation.

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