使用指针的二叉搜索树问题

Question

I'm relatively new to coding in C++. I'm trying to make a BST in C++ and I'm using pointers for this but I can't figure out the error in pointers even after spending hours of time. Basically, the error comes in the if statement, where I'm trying to use recursion to change root when there are children present from parent root.
Here is the code

#include<iostream>
using namespace std;

struct node{
    struct node* rightchild;
    int data;
    struct node* leftchild;
};

struct node* newNode(int data){
    struct node* node1 = (node*)malloc(sizeof(node));
    (*node1).data=data;
    (*node1).leftchild = NULL;
    (*node1).rightchild = NULL;
    return node1;
}

void insertIntoBST(struct node** ptrtoroot, struct node** ptrtotemp){
    if((**ptrtotemp).data <= (**ptrtoroot).data){
        if((**ptrtoroot).leftchild != NULL){
            insertIntoBST((*ptrtoroot).leftchild,(*ptrtotemp));
        }
        else{
           (*ptrtoroot->leftchild) = *ptrtotemp;
        }
    }
     if((**ptrtotemp).data > (**ptrtoroot).data){
        if((**ptrtoroot).rightchild != NULL){
            insertIntoBST((*ptrtoroot->rightchild),(*ptrtotemp));
        }
        else{
           (*ptrtoroot->rightchild) = *ptrtotemp;
        }
    }
    
}

void inorder(struct node* root){
    while(root != NULL){
        cout<<(*root).data;
        inorder((*root).leftchild);
        inorder((*root).rightchild);
    }
}

int main(){
    struct node* root = NULL;
    struct node* temp;
    int dat;
    for(int i = 0 ; i < 6 ; i++){
    cin>>dat;
    temp = newNode(dat);
    if(root == NULL){
        root = temp;
    }
    else{
        insertIntoBST(&root,&temp);
    }
 }
 inorder(root);

    return 0;
}

Error code:

bst.cpp:21:40: error: request for member ‘leftchild’ in ‘* ptrtoroot’, which is of pointer type ‘node*’ (maybe you meant to use ‘->’ ?)  
21 | insertIntoBST((ptrtoroot).leftchild,(*ptrtotemp));  
   | ^~~~~~~~~ bst.cpp:24:25: error: request for member ‘leftchild’ in ‘ ptrtoroot’, which is of pointer type ‘node*’ (maybe you meant to use ‘->’ ?)  
24 | (*ptrtoroot->leftchild) = *ptrtotemp;  

Answer 1

Okay by looks of it I think in your function as shown below.

void insertIntoBST(struct node** ptrtoroot, struct node** ptrtotemp){
    if((**ptrtotemp).data <= (**ptrtoroot).data){
        if((**ptrtoroot).leftchild != NULL){
            insertIntoBST((*ptrtoroot).leftchild,(*ptrtotemp));

ptrtoroot is double pointer ie pointer to pointer so this makes (*ptrtoroot) a pointer and here

(*ptrtoroot).leftchild should be replaced with "->" operator 
like (*ptrtoroot)->leftchild

Secondly under recursive calls insertIntoBST function takes double pointer as argument so you need to pass address of pointer here.

ie Address of a pointer returned by (*ptrtoroot)->leftchild from your node structure.

something like &((*ptrtoroot)->leftchild)

I have not completely executed your code but this should work.

Same goes for the second parameter (*ptrtotemp).