c++ - create a BST of string . error -

inserting 1 node tree works fine, on inserting 2nd node onwards, program crashes. here code:

#include <iostream> #include <cstring>  using namespace std; struct node {      char* key;     node *left, *right; };  // utility function create new bst node node *newnode(const char* item) {     node *temp =new node;     strcpy(temp->key,item);     temp->left = temp->right = null;     return temp; }  // utility function inorder traversal of bst void inorder(node *root) {     if (root!= null)     {         inorder(root->left);         cout<<root->key<<endl;         inorder(root->right);     } }  /* utility function insert new node given key in bst */ node* insert(node* tnode,const char* key) {     /* if tree empty, return new node */      if (tnode == null)         return newnode(key);     /* otherwise, recur down tree */     if (strcmp(key,tnode->key) < 0)         tnode->left  = insert(tnode->left, key);     else if (strcmp(key,tnode->key) > 0)         tnode->right = insert(tnode->right, key);      /* return (unchanged) node pointer */     return tnode; }  // driver program test above functions*/ int main() {     node *root = null;      char* word[]={"elephant","hi","little","nil",null};     root = insert(root,word[0]);                //works fine for(int i=1;word[i];i++)     insert(root,word[i]);                                     // print inoder traversal of bst     inorder(root);      return 0; } 

after:

root = insert(root,word[0]);

inorder(root);

o/p: elephant

on inserting 2nd node

crashes

you're not initialising key array item copied into. try this:

node *newnode(const char* item) {     node *temp = new node();     temp->key = new char[strlen(item) + 1];     strcpy(temp->key,item);     temp->left = temp->right = null;     return temp; } 

that said, there more problems code, no destructors etc. i'd recommend reading books/tutorials on programming in c++.