将2D切片传递给Golang函数参数

Question

I'm trying to scan a matrix from the stdin and simply print it using following code.

package main

import (
    "fmt"
)

func print2D(arr [][]int) {
    for i:=0; i< len(arr); i++{
        for j := 0; j< len(arr[0]); j++{
            fmt.Printf("%d ", arr[i][j])
        }
        fmt.Println()
    }
}

func main() {
    var arr [6][6]int
    for i:= 0 ; i < 6 ;i++ {
        for j := 0; j< 6; j++{
            fmt.Scanf("%d", &arr[i][j])
        }
    }
    print2D(arr[:])
}

It throws the following error

./main.go:23: cannot use arr[:] (type [][6]int) as type [][]int in argument to print2D

Is there a way to pass a 2D slice without defining sizes in the function arguments?

Answer 1

Try to write the data directly to the slice and pass it later to the function. Remember array and slices are different types. Moreover, the type [3]int is also different from [4]int (size matters).

package main

import (
    "fmt"
)

func print2D(arr [][]int) {
    for i := 0; i < len(arr); i++ {
        for j := 0; j < len(arr[0]); j++ {
            fmt.Printf("%d ", arr[i][j])
        }
        fmt.Println()
    }
}

func main() {
    var arr [][]int
    for i := 0; i < 6; i++ {
        tmp := make([]int, 6)
        for j := 0; j < 6; j++ {
            fmt.Scanf("%d", &tmp[j])
        }
        arr = append(arr, tmp)
    }
    print2D(arr)
}