Printing the cart
- Go course
- Beginner
- Lesson 50/90
- 6 min
Format and print the cart with fmt.Printf.
Printing the cart
To print the cart as a readable table, Printf width and precision fields are used:
for _, u := range s.Urunler {
fmt.Printf("%-8s %3d x %6.2f = %7.2f\n", u.Ad, u.Adet, u.Fiyat, u.AraToplam())
}
fmt.Printf("%-8s %22.2f\n", "TOPLAM", s.Toplam())%-8s left-aligns the name in 8 characters and %6.2f writes the number in 6 characters with 2 decimals.
The cart as a Stringer
If a String() string method is added to the cart, fmt.Println(s) prints the cart in its own format. To build the text piece by piece, strings.Builder and fmt.Fprintf are used together:
func (s Sepet) String() string {
var b strings.Builder
for _, u := range s.Urunler {
fmt.Fprintf(&b, "%s x%d\n", u.Ad, u.Adet)
}
return b.String()
}Practice Cart receipt
With Urun (and AraToplam), print two products in the format fmt.Printf("%-8s %2d x %5.2f = %6.2f\n", ...): Kalem 12.5 × 2 and Defter 20 × 1.
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
type Urun struct {
Ad string
Fiyat float64
Adet int
}
func (u Urun) AraToplam() float64 { return u.Fiyat * float64(u.Adet) }
func main() {
for _, u := range []Urun{{"Kalem", 12.5, 2}, {"Defter", 20, 1}} {
fmt.Printf("%-8s %2d x %5.2f = %6.2f\n", u.Ad, u.Adet, u.Fiyat, u.AraToplam())
}
}Expected output
Kalem 2 x 12.50 = 25.00 Defter 1 x 20.00 = 20.00
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the output of <code>fmt.Printf("%6.2f", 7.5)</code>?
- "000007.50"
- " 7.50" Correct answer
- "7.50"
- "7.5 "
Explanation: Width 6 with two decimals: "7.50" is 4 characters, so 2 spaces are added in front.
2 Left-align
fmt.Printf("____|
", "Kalem") // "Kalem |"fmt.Printf("%-8s|
", "Kalem") // "Kalem |"Explanation: %-8s left-aligns text in an 8-character field.
3 Format and effect
| Term | Meaning |
|---|---|
%-8s |
Left-aligned text |
%3d |
3-wide number |
%6.2f |
2 decimals, width 6 |
String() |
Println format |