douyan2680
2018-09-20 09:54 阅读 104
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Golang中[] [] *数据类型是什么意思

Suppose this is my sample code. On running it outputs [[]][[] []][[] [] []][[] [] [] []]. Help me in understanding what this code is depicting and what is routingtable [][]*node called in programming terminology. Is it a slice of slice of node or is it a 2d array of node type. Forgive me if I sound dumb but I am just trying to learn.

package main

import "fmt"

type node struct {
    id int
}

func main() {
    var routingtable [][]*node

    for i := 0; i < 4; i++ {
        routingtable = append(routingtable, []*node{})
        fmt.Print(routingtable)
    }
}
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1条回答 默认 最新

  • 已采纳
    dongmo20030416 dongmo20030416 2018-09-20 09:57

    It simply means it contains 4 empty node pointer slices, which is the expected behavior from your code.

    It is a slice of slices of node pointers.

    Here is a simple modification of your code to show you how it works if you add nodes to your slices:

    package main
    
    import "fmt"
    
    type node struct {
        id int
    }
    
    func main() {
        var routingTable [][]*node
        for i := 0; i < 4; i++ {
            routingTable = append(routingTable, []*node{&node{id: i}})
        }
        fmt.Print(routingTable)
    }
    

    Will output the slice of slices of node pointers, containing one node each with a different address:

    [[0x10414020] [0x10414024] [0x10414028] [0x1041402c]]
    

    Try it yourself here

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