自引用结构

可以使用结构定义二叉树结构。

#include <stdio.h>

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

int main(int argc, char const *argv[])
{
    struct node rootNode, leftNode, rightNode;
    rootNode.data = 1;
    rootNode.left = &leftNode;
    rootNode.right = &rightNode;
    leftNode.data = 2;
    leftNode.left = NULL;
    leftNode.right = NULL;
    rightNode.data = 3;
    rightNode.left = NULL;
    rightNode.right = NULL;
    printf("root: %d.\n", rootNode.data);
    printf("left: %d.\n", rootNode.left->data);
    printf("right: %d.\n", rootNode.right->data);
    return 0;
}

执行下面的代码，动态分配结构的存储空间。

#include <stdio.h>
#include <stdlib.h>

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

int main(int argc, char const *argv[])
{
    struct node *rootNode = (struct node *)malloc(sizeof(struct node));
    struct node *leftNode = (struct node *)malloc(sizeof(struct node));
    struct node *rightNode = (struct node *)malloc(sizeof(struct node));
    rootNode->data = 1;
    rootNode->left = leftNode;
    rootNode->right = rightNode;
    leftNode->data = 2;
    leftNode->left = NULL;
    leftNode->right = NULL;
    rightNode->data = 3;
    rightNode->left = NULL;
    rightNode->right = NULL;
    printf("root: %d.\n", rootNode->data);
    printf("left: %d.\n", rootNode->left->data);
    printf("right: %d.\n", rootNode->right->data);
    free(rootNode);
    free(leftNode);
    free(rightNode);
    return 0;
}