在Go中遍历多维数组

Question

In the following code example

var a [3][5]int8
for _, h := range a {
    for _, cell := range h {
        fmt.Print(cell, " ")
    }
    fmt.Println()
}

is the copy of a row of a made in every iteration? i.e., does h contain a copy of a row of a or does h get a reference to it?

Answer 1

A copy. For example,

package main

import "fmt"

func main() {
    var a [3][5]int8
    fmt.Println(a)
    for _, h := range a {
        h = [5]int8{1, 2, 3, 4, 5}
        for _, cell := range h {
            fmt.Print(cell, " ")
        }
        fmt.Println()
    }
    fmt.Println(a)

}

Output:

[[0 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0]]
1 2 3 4 5 
1 2 3 4 5 
1 2 3 4 5 
[[0 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0]]

The Go Programming Language Specification

For statements

A "for" statement with a "range" clause iterates through all entries of an array, slice, string or map, or values received on a channel. For each entry it assigns iteration values to corresponding iteration variables and then executes the block.

The iteration values are assigned to the respective iteration variables as in an assignment statement.