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Array won’t change
source link: https://yourbasic.org/golang/gotcha-function-doesnt-change-array/
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Array won’t change
yourbasic.org/golang
Why does the array value stick?
func Foo(a [2]int) {
a[0] = 8
}
func main() {
a := [2]int{1, 2}
Foo(a) // Try to change a[0].
fmt.Println(a) // Output: [1 2]
}Answer
- Arrays in Go are values.
- When you pass an array to a function, the array is copied.
If you want Foo to update the elements of a, use a slice instead.
func Foo(a []int) {
if len(a) > 0 {
a[0] = 8
}
}
func main() {
a := []int{1, 2}
Foo(a) // Change a[0].
fmt.Println(a) // Output: [8 2]
}A slice does not store any data, it just describes a section of an underlying array.
When you change an element of a slice, you modify the corresponding element of its underlying array, and other slices that share the same underlying array will see the change.
See Slices and arrays in 6 easy steps for all about slices in Go.
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