meet it

Big programs are small pieces working as a team.

A bundles values into one, like a pet's record card. type Pet struct lists its fields, each with a name and a type. Make a card with Pet{Name: "Rex", Age: 3}, and read a with a dot: pet.Name.

Real programs are built from small parts. A slice of structs holds the data, a loop walks through it, a function answers one question and an if decides what to do.

When something goes wrong, you : find the bug, fix it, run again. Every programmer does this every day. Small functions help, because you can test each one on its own.

package main
import "fmt"
type Pet struct {
	Name string
	Age  int
}
func main() {
	pets := []Pet{{Name: "Rex", Age: 3}, {Name: "Tibbles", Age: 12}}
	for _, pet := range pets {
		fmt.Printf("%v is %v\n", pet.Name, pet.Age)
	}
}

Inside a slice of Pet, you can leave out the word Pet before each card's curly brackets.

guess first

Prices have doubled. What will this show?

Guess before you run it. Wrong guesses are how you learn, and nothing is marked.

package main
import "fmt"
type Snack struct {
	Name  string
	Price int
}
func main() {
	snack := Snack{Name: "crisps", Price: 2}
	snack.Price = snack.Price * 2
	fmt.Println(snack)
}

your turn

Your turn. Fill in a pet's record card.

Make a record card for a pet, real or made up. Type its name between the quotes and its age as a whole number. The describe function does the rest.

Your code

output

press run to see what happens

fix it

The wise old cat cannot be found. Debug it!

Broken code to fix

output

press run to see what happens

Read the error on line 9. Which field does Go say it cannot find?
Go is case-sensitive. The struct's field is called Age, with a capital A.
Change pet.age to pet.Age on line 9, then run.

nailed it

you put all the pieces together. :D

A struct bundles named fields, like a record card.
Read a field with a dot, like pet.Name.
To debug, find the bug, fix it, then run again.

new words in your collection

struct
field
debug

This lesson isn’t saved. A free account remembers every lesson you finish.