douguaidian8021
douguaidian8021
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2018-08-14 19:55 阅读 469
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在golang中创建二维字符串数组

I need to create a 2 dimensional string array as shown below -

matrix = [['cat,'cat','cat'],['dog','dog']]

Code:-

package main

import (
    "fmt"
)

func main() {
    { // using append

    var matrix [][]string
    matrix[0] = append(matrix[0],'cat')
        fmt.Println(matrix)
    }
}

Error:-

panic: runtime error: index out of range

goroutine 1 [running]:
main.main()
    /tmp/sandbox863026592/main.go:11 +0x20
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2条回答 默认 最新

  • 已采纳
    duanjue2560 duanjue2560 2018-08-14 20:05

    You have a slice of slices, and the outer slice is nil until it's initialized:

    matrix := make([][]string, 1)
    matrix[0] = append(matrix[0],'cat')
    fmt.Println(matrix)
    

    Or:

    var matrix [][]string
    matrix = append(matrix, []string{"cat"})
    fmt.Println(matrix)
    

    Or:

    var matrix [][]string
    var row []string
    row = append(row, "cat")
    matrix = append(matrix, row)
    
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  • dongyijing2353 dongyijing2353 2019-05-18 01:04

    The problem with doing two-dimensional arrays with Go is that you have to initialise each part individually, e.g., if you have a [][]bool, you gotta allocate []([]bool) first, and then allocate the individual []bool afterwards; this is the same logic regardless of whether you're using make() or append() to perform the allocations.

    In your example, the matrix[0] doesn't exist yet after a mere var matrix [][]string, hence you're getting the index out of range error.

    For example, the code below would create another slice based on the size of an existing slice of a different type:

    func solve(board [][]rune, …) {
    
        x := len(board)
        y := len(board[0])
        visited := make([][]bool, x)
        for i := range visited {
            visited[i] = make([]bool, y)
        }
    …
    

    If you simply want to initialise the slice based on a static array you have, you can do it directly like this, without even having to use append() or make():

    package main
    
    import (
        "fmt"
    )
    
    func main() {
        matrix := [][]string{{"cat", "cat", "cat"}, {"dog", "dog"}}
        fmt.Println(matrix)
    }
    

    https://play.golang.org/p/iWgts-m7c4u

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