如何更新转到列表中的下一个指针？

Question

I have a node pointer from the list. I want update the value and next pointer with the next node in the list. This is nothing but deletion in place given access to only that pointer.

For example 3 -> 5 -> 8 -> 9 Node to be deleted : 5 (given access to only 5. Assuming previous node is not known)

In this case the value and next pointer of node[8] can be copied to node[5]. I have the following code. It is not removing the element. If I try to access the next pointer using 'next' keyword it is throwing error.

package main
import (
    "container/list"
    "fmt"
)

func main() {

    l := list.New()
    l.PushFront(4)
    l.PushFront(5)
    e4 := l.PushFront(7)
    l.PushFront(6)
    l.PushBack(9)
    res := deleteNode(e4)
    fmt.Println(res)

    for e:=l.Front(); e!=nil;e=e.Next() {
        fmt.Println(e.Value)
    }

}
//ERROR
func deleteNode(node *list.Element) bool {

    if node == nil || node.Next() == nil {
        return false
    }
    var nextNode *list.Element 
    nextNode := node.next.(*list.Element)
    node.Value = node.Next().Value.(int)
    nextNode = nextNode.next.(*Element)
    return true
}

Could anyone help me with this?

Answer 1

The (first) error you get is:

no new variables on left side of :=

Because nextNode already exists. The problem is with these 2 lines:

var nextNode *list.Element 
nextNode := node.next.(*list.Element)

In the first line you create the variable nextNode . In the second line you use the short assignment := which creates a new variable (specified by the left side) and assigns to it the value on the right side. Just leave out the first line, you only need one of those:

nextNode := node.Next()

Moreover you cannot read or change the next pointer of a node because the next pointer is not exported in the Element struct (it starts with lowercased letter). So what you try to achieve cannot be done. But you have a function defined for this: Remove(e *Element) interface{}