Array declaration
- Go course
- Beginner
- Lesson 41/90
- 4 min
Learn to declare fixed-size arrays.
Defining arrays
An array is a fixed-length sequence of elements of the same type. The length is part of the type: [3]int and [4]int are different types.
var notlar [3]int // [0 0 0]
notlar[0] = 90
gunler := [...]string{"Pzt", "Sal", "Çar"} // length 3
fmt.Println(notlar, len(gunler))Indexes start at 0; an out-of-range index errors at compile or run time.
When to use arrays
Arrays suit small data whose length is known exactly at compile time: an RGB color ([3]uint8), a chessboard ([8][8]Tas), a SHA-256 digest ([32]byte). Arrays can be compared with == and can be map keys. In everyday code the flexible-length slice is used most of the time.
Practice Array average
Declare notlar := [4]int{70, 85, 90, 55}. Sum it with for, compute the average as a float64 and print it.
Starter code
package main
import "fmt"
func main() {
// buraya yaz
}Sample solution
package main
import "fmt"
func main() {
notlar := [4]int{70, 85, 90, 55}
toplam := 0
for _, n := range notlar {
toplam += n
}
fmt.Println(float64(toplam) / float64(len(notlar)))
}Expected output
75
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What happens when an array is assigned to another variable?
- Only the first element is copied
- A compile error
- All elements are copied Correct answer
- They share the same memory
Explanation: Arrays are value types; changing b after b := a doesn't affect a. Slices, by contrast, share the same array.
2 Count the length
renk := [____]uint8{255, 128, 0}renk := [...]uint8{255, 128, 0}Explanation: [...] lets the compiler infer the length from the number of elements.
3 Expression and result
| Term | Meaning |
|---|---|
var a [3]int |
[0 0 0] |
len([5]int{}) |
5 |
[3]int == [4]int |
Different types, not comparable |
b := a |
A copy |