Binary Search Tree Newnode segmentation fault

Question

I'm trying to create a binary search tree from a given array. The following code shows segmentation fault. I tried debugging it and found problem on the *newnode function.

#include <iostream>
using namespace std;

struct node
{
    int data;
    struct node *left;
    struct node *right;
    struct node *parent;
};

struct node *newnode(int data)
{
    struct node *temp;
    temp->data = data;
    temp->right =NULL;
    temp->left = NULL;
    temp->parent =NULL;
    return(temp);
}

The above function seems to return the correct pointer but the in the following function T doesn't seem to accept it.

void Insert(struct node *T,int data)
{
    if(T==NULL)
    {
      T = newnode(data); //The program shows segfault here.
     return;
    }
    if(data>T->data) { Insert(T->right,data); T->right->parent = T; }
    else { Insert(T->left,data); T->left->parent = T; }

    return;
}

void Inorder(struct node *T)
{
    if(T==NULL) return;
    else{

        Inorder(T->left);
        cout<<T->data<<" ";
        Inorder(T->right);
    }
}

int main() {

    int n; cin>>n;
    struct node *tree=NULL;
    for(int i=0;i<n;i++)
    {
        int x; cin>>x;
        Insert(tree,x);
    }

    Inorder(tree);

    return 0;
}

Answer 1

You have not allocated memory to temp pointer.

struct node *newnode(int data)
{
    struct node *temp = new node;   
    temp->data = data;
    temp->right = NULL;
    temp->left = NULL;
    temp->parent = NULL;
    return temp;
}