typedef struct node{
    elem_type data;
    struct node *lchild;
    struct node *rchild;
}tree_node,*tree_ptr;

int init_node(tree_ptr *pnode)
{
    pnode = (tree_ptr)malloc(sizeof(tree_node));
    if(pnode == NULL){
        printf("fail: malloc failed\n");
        exit(0);
    }
    pnode->lchild = pnode->rchild = NULL;
    pnode->data = 0;
    return 0;
}

上面pnode = (tree_ptr)malloc(sizeof(tree_node));
    pnode->lchild = pnode->rchild = NULL;
    pnode->data = 0;
这三条语句有错么？？望高手指点.....谢谢！