c - Infinite loop in iterative preorder traversal of BST -

i trying iteratively traverse bst in preorder, function getting stuck in infinite loop while printing. please tell me why happening?

1 typedef struct node_{ 2     int data; 3     struct node_* left; 4     struct node_* right; 5 }bst;   22 void preorder(bst* tree){ 23     if(tree==null){ 24         return; 25     } 26     // create stack  27     stack* stack=create_stack(); 28     // push data onto stack 29     push(stack,tree->data); 30     while(isempty(stack)==0){ 31         struct node_ *node; 32         node->data=top(stack); 33         printf("%d ",node->data); 34         // pop value off stack 35         pop(stack); 36         if(node->right!=null){ 37             //push right child onto stack 38             push(stack,node->right->data); 39         } 40         if(node->left!=null){ 41             // push left child onto stack 42             push(stack,node->left->data); 43         } 44     } 45 } 

your loop never ends because node->right , node->left point random memory locations. value of node? haven't assigned it. value random.

another problem you're pushing tree->data onto stack. want push tree onto stack. can pop node off stack , assign node. can print node->data , check children of node.