How to create a binary tree use struct in golang?

I want to create a binary tree and initialize the tree use golang.
And the codes like these:

package Tree

import "fmt"

type TreeNode struct {
	Left  *TreeNode
	Right *TreeNode
	Value int
}


func InsertNodeToTree(tree *TreeNode, node *TreeNode)(){
	if tree == nil {
		tree = node
	}
	if node.Value > tree.Value {
		InsertNodeToTree(tree.Right, node)
	}
	if node.Value < tree.Value {
		InsertNodeToTree(tree.Left, node)
	}
}

func InitTree(values ...int) (root *TreeNode) {
	rootNode := TreeNode{Value: values[0]}
	for _, value := range values {
		node := TreeNode{Value:value}
		InsertNodeToTree(&rootNode, &node)
	}
	return &rootNode
}

func main() {
	treeNode := InitTree(5, 4, 6, 8, 9, 7, 1, 3, 2)
	fmt.Println(treeNode)
}

Why the tree's left and right are nil?
I pass the reference of the tree node, why not work?

tree is only a copy of the pointer. Assigning to the variable is useless. Instead, you need to assign to an already existing node. For example:

https://play.golang.org/p/Agzby-Yinq

func InsertNodeToTree(tree *TreeNode, node *TreeNode) {
	if tree == nil {
		panic("cannot insert into nil root")
	}

	if node.Value > tree.Value {
		if tree.Right == nil {
			tree.Right = node
		} else {
			InsertNodeToTree(tree.Right, node)
		}
	}
	if node.Value < tree.Value {
		if tree.Left == nil {
			tree.Left = node
		} else {
			InsertNodeToTree(tree.Left, node)
		}
	}
}

In C/C++ programming language, you can use TreeNode *&tree.<br/>
But in golang programming language, you can not use *&.<br/>
tree is just a copy of the pointer, so you can't point the value to another TreeNode.<br/>
I modified your program, and it can run successfully now.<br/>
Maybe these codes you need:

package Tree

type TreeNode struct {
	Left  *TreeNode
	Right *TreeNode
	Value int
}


var DefaultValue int = -1024


func InsertNodeToTree(tree *TreeNode, node *TreeNode)(){
	if tree == nil {
		return
	}
	if tree.Value == DefaultValue {
		tree.Value = node.Value
		return
	}
	if node.Value > tree.Value {
		if tree.Right == nil {
			tree.Right = &TreeNode{Value: DefaultValue}
		}
		InsertNodeToTree(tree.Right, node)
	}
	if node.Value < tree.Value {
		if tree.Left == nil {
			tree.Left = &TreeNode{Value: DefaultValue}
		}
		InsertNodeToTree(tree.Left, node)
	}
}

func InitTree(values ...int) (root *TreeNode) {
	rootNode := TreeNode{Value: DefaultValue, Right: nil, Left: nil}
	for _, value := range values {
		node := TreeNode{Value:value}
		InsertNodeToTree(&rootNode, &node)
	}
	return &rootNode
}