如何传递创建二维数组的切片

Question

I am having trouble to pass a slice of a 2d array of strings inside a func : this is my playground

Golang playground

package main

import (
    "fmt"
)

func main() {
    board := [2][3]string{
        {"O", "_", "O"},
        {"X", "O", "_"},
    }

    printBoard(board[:][:])
}

func printBoard(board [][]string){
    for _, line := range board {
        for _, cell := range line {
            fmt.Printf("%s", cell)
        }
        fmt.Println()
    }
}

It says cannot use board[:][:] (type [][3]string) as type [][]string in argument to printBoard

I did not manage to correct it printBoard(board[:][:]).

I tried by removing one/both semicolons inside the call, but did not work either. I do not want to specify any length if possible

Answer 1

In go, arrays have fixed sizes contrary to slices, so here you need to specify the size of your array as the argument, otherwise you will get this error:

prog.go:13:12: cannot use board (type [2][3]string) as type [][]string in argument to printBoard

Here it is fixed:

package main

import (
    "fmt"
)

func main() {
    board := [2][3]string{
        {"O", "_", "O"},
        {"X", "O", "_"},
    }

    printBoard(board)
}

func printBoard(board [2][3]string){
    for _, line := range board {
        for _, cell := range line {
            fmt.Printf("%s", cell)
        }
        fmt.Println()
    }
}

Outputs

O_O
XO_

I'm not sure why you decided to use arrays but in go, whenever possible you should prefer using slices instead of arrays, as they're more flexible, cleaner and less bug-prone.

Here is the implementation with slices instead:

package main

import (
    "fmt"
)

func main() {
    board := [][]string{
        {"O", "_", "O"},
        {"X", "O", "_"},
    }

    printBoard(board)
}

func printBoard(board [][]string){
    for _, line := range board {
        for _, cell := range line {
            fmt.Printf("%s", cell)
        }
        fmt.Println()
    }
}

Note that you don't need to change your logic, and you don't need to specify sizes anywhere anymore.