C指针的结构和引用的指针

Question

我正在尝试在C中实现BST。这是代码：

int main(int argc, char* argv[]) {
    int_bst_node_t * tree_p = NULL;
    test_insert(&tree_p, 40);
}

static void test_insert(int_bst_node_t ** t_p, int n) {
    printf("inserting %d into tree ", n);
    printf("\n");
    if (int_bst_insert(t_p, n)) {
        printf("result ");
        print_tree_elements(*t_p);
        printf("\n");
    }
    else {
       printf("insert failed\n");
    }
}

其他文件中的代码：

// Create a node, assign values
bool createNode(int n, int_bst_node_t *node) {
    int_bst_node_t *localNode = (struct int_bst_node*)malloc(sizeof(int_bst_node_t));
    if( localNode == NULL )
    {
        puts("\n Unable to allocate memory");
        return false;
    }
    localNode->data = n;
    localNode->left = NULL;
    localNode->right = NULL;

    node = localNode;
    //////    Prints right values 
    printf("\n LocalNode Data: %d  Node Data: %d", localNode->data, node->data);
    free(localNode);
    return true;
}

/* 
 * insert n into *t_p
 * does nothing if n is already in the tree
 * returns true if insertion succeeded (including the case where n is already
 * in the tree), false otherwise (e.g., malloc error)
*/
bool int_bst_insert(int_bst_node_t ** t_p, int n) {
    if (*t_p == NULL) {
        printf("*t_p %d IS null", *t_p);
        int_bst_node_t node;
        // Pass node as a ref, so data is updated
        if (createNode(n, &node) == false)
            return false;

        // Prints invalid data
        printf("\n Data of new node : %d", node.data);
        *t_p = &node;

        /*
          Need  to assign node to *t_p, so it is updated, and prints the values
          when calling next function in test_insert()

        int_bst_node_t *t = *t_p;
        printf("\n Data of *tp node : %d", t->data);  
        */     
     } else 
        printf("*t_p %d is NOT null", *t_p);

    printf("\n"); 
    return true;
 }

我无法将节点的值/ ref设置为t_p。这仅适用于根节点；更进一步，它将有更多的节点。我无法获得**的概念来更新值。我尝试了变体，但都失败了。

[如果有人可以帮助我，我会很高兴。

谢谢。

我正在尝试在C中实现BST。这是代码：int main（int argc，char * argv []）{int_bst_node_t * tree_p = NULL; test_insert（＆tree_p，40）; }静态无效test_insert（...

Answer 1

函数createNode至少没有意义，因为它接受按值指向节点的指针。在为节点分配内存后，您立即释放它，使指向已分配内存的指针无效。