Trying to test for an empty self referential struct value in Go

Question

I am new to Go and am trying to implement a very simple linked list. Currently while recursively traversing the list I am attempting to break out of the for loop if node.next is nil/unset, but the if conditional is never satisfied. I can only assume that the value is not nil, but some sort of pointer to an empty Node struct type, but I can't figure out how to evaluate this. Here is my code, any help would be much appreciated:

package main

import "fmt"

type Node struct {
    data string
    next *Node
}

func PrintList(node *Node) {
  for {
    fmt.Println(node.data)

    if node.data == nil {
      break
    } else {
      PrintList(node.next)
    }
  }
}

func main() {
  node3 := &Node{data: "three"}
  node2 := &Node{data: "two", next: node3}
  node1 := &Node{data: "one", next: node2}

  PrintList(node1)
}

peterSO · Accepted Answer · 2016-03-05 14:57:13Z

3

Fix your typo:node.next == nil not node.data == nil. And fix your recursion error: delete the for loop. Even better, for safety, check for node == nil. For example,

package main

import "fmt"

type Node struct {
    data string
    next *Node
}

func PrintList(node *Node) {
    if node == nil {
        return
    }
    fmt.Println(node.data)
    PrintList(node.next)
}

func main() {
    node3 := &Node{data: "three"}
    node2 := &Node{data: "two", next: node3}
    node1 := &Node{data: "one", next: node2}
    PrintList(node1)
}

Output:

one
two
three

edited Mar 5, 2016 at 14:57

answered Mar 5, 2016 at 14:36

peterSO

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