bst检查root是否为NULL时插入段错误

Question

我正在尝试向bst插入值，但是当我在插入之前检查root是否为NULL时，我得到了一个段错误。如何首先将树初始化为NULL或我做错了什么？

void StdClass::add(int val, ...){
    Node *temp, *parent;

    if (root == NULL) {//throws segfault here..
        root = new Node(...);
        root->left = NULL;
        root->right = NULL;
        temp = root;
        return;
    } else {
        temp=root;
        while (temp!=NULL) {
            if (val <= temp->key){
                parent = temp;
                temp=temp->left;
                //root =temp;
                return;
            } else {
                parent =temp;
                temp=temp->right;
                //root=temp;
                return;
            }
        }
        Node *newNode = new Node(...);
        newNode->left = NULL;
        newNode->right = NULL;

    //Now insert the new node BELOW parent
    if(val <= parent->key){
        parent->left = newNode;}
    else{
        parent->right = newNode;
    }
}

}

root是在StdClass中私有定义的。

struct Node{
    int key;
    std:string b;
    std::string c;

    Node *parent;
    Node *left;
    Node *right;

    Node(){};

    Node(int val, std::string s, std::string t){
        key = val;
        b= s;
        c = t;

    }
}
Class StdClass{
    public:
        void add(int, std::string, std::string);
    private:
        Node *root;
}

从另一个函数调用它..

void StdClass::test(){
    int x = 0;
    while(x < 10){
        add(x,"test","test");
        x++;
    }
}

的main.cpp

#include "StdClass.h"
int main(){
    StdClass s;
    s.test();
    return 0;
}