Go Project: Shopping Basket
The Shopping Basket project stores items in a named slice type. It adds up a receipt and prints a sorted summary.
One Item
The Item struct holds a name, a price, and a quantity. One line of the receipt comes from its fields.
package main
import "fmt"
type Item struct {
Name string
Price int
Qty int
}
func main() {
item := Item{Name: "Pen", Price: 3, Qty: 2}
fmt.Println(item.Name, item.Qty, item.Price*item.Qty)
}Add an Item
Add appends an item to the basket. The basket then holds one item.
package main
import "fmt"
type Item struct {
Name string
Price int
Qty int
}
type Basket []Item
func (b *Basket) Add(item Item) {
*b = append(*b, item)
}
func main() {
var basket Basket
basket.Add(Item{Name: "Pen", Price: 3, Qty: 2})
fmt.Println(len(basket))
fmt.Println(basket[0].Name)
}Total the Basket
Total adds price times quantity for each item. Two items give a total of 18.
package main
import "fmt"
type Item struct {
Name string
Price int
Qty int
}
type Basket []Item
func (b *Basket) Add(item Item) {
*b = append(*b, item)
}
func (b Basket) Total() int {
total := 0
for _, item := range b {
total += item.Price * item.Qty
}
return total
}
func main() {
var basket Basket
basket.Add(Item{Name: "Pen", Price: 3, Qty: 2})
basket.Add(Item{Name: "Book", Price: 12, Qty: 1})
fmt.Println(basket.Total())
}Example
package main
import (
"fmt"
"slices"
"strings"
)
type Item struct {
Name string
Price int
Qty int
}
type Basket []Item
func (b *Basket) Add(item Item) {
*b = append(*b, item)
}
func (b Basket) Total() int {
total := 0
for _, item := range b {
total += item.Price * item.Qty
}
return total
}
func main() {
var basket Basket
basket.Add(Item{Name: "Pen", Price: 3, Qty: 2})
basket.Add(Item{Name: "Book", Price: 12, Qty: 1})
basket.Add(Item{Name: "Mug", Price: 8, Qty: 1})
count := 0
names := []string{}
for _, item := range basket {
fmt.Println(item.Name, item.Qty, item.Price*item.Qty)
count += item.Qty
names = append(names, item.Name)
}
fmt.Println("Items:", count)
fmt.Println("Total:", basket.Total())
slices.Sort(names)
fmt.Println(strings.Join(names, ", "))
}Key points
- Item holds the name, price, and quantity of one product.
- Basket is a named slice type that holds items.
- Add uses a pointer receiver, so the appended item stays in the basket.
- Total sums price times quantity for every item.
- The receipt prints items in the order they were added.
- The summary sorts a separate names slice, so the basket order stays unchanged.
In this example, Add puts the Pen, the Book, and the Mug into the basket in that order. The loop prints one receipt line per item with its line total. The loop also counts the quantities, which add up to 4, and collects the names. Total adds the line totals into 26. The names are sorted and joined for the last line.
Try it Yourself
Edit the code, then press Run.
Running is simulated · Go Playground
Exercise
Why does Add use a pointer receiver?