[c]一个简单的二叉树

使用C语言练练手避免手生。

文件主要有三个: bst.h, bst.c, test_bst.c

文件bst.h

typedef enum {FALSE=0, TRUE=1} bool;/* * Define a node structure. */typedef struct node {  int val;  struct node* left;  struct node* right;} node_t;/* * Creates a new node from a given value, allocating heap memory for it. */node_t* make_tree(int val);/* * Inserts a new value into a given binary search tree, allocating heap memory * for it. */node_t* insert(int val, node_t* cur_root);bool find_val(int val, node_t* root);/* * Given a pointer to the root, frees the memory associated with an entire list. */void delete_bst(node_t* root);/* Given a pointer to the root, prints all of the values in a tree. */// pre order visitingvoid print_bst(node_t* root);

文件 bst.c

#include <stdio.h>#include <stdlib.h>#include "bst.h"/* * Creates a new node from a given value, allocating heap memory for it. */node_t* make_tree(int val) {  node_t* new_tree = malloc(sizeof(node_t));  new_tree->val = val;  new_tree->left = NULL;  new_tree->right = NULL;  return new_tree;}/* * Inserts a new value into a given binary search tree, allocating heap memory * for it. */node_t* insert(int val, node_t* cur_root) {  /* always return root node */    node_t* left_node;    node_t* right_node;    node_t* new_node;    node_t* root;    root = cur_root;    while(cur_root != NULL){        left_node = cur_root->left;        right_node = cur_root->right;        if(val < cur_root->val){            if(left_node == NULL){                new_node = make_tree(val);                cur_root->left = new_node;                return root;            }            else{                cur_root = cur_root->left;            }        }        else if(val > cur_root->val){            if(right_node == NULL){                new_node = make_tree(val);                cur_root->right = new_node;                return root;            }            else{                cur_root = cur_root->right;            }        }        else{            // the val has been inserted            return NULL;        }    }    //empty tree    cur_root = make_tree(val);    return cur_root;}bool find_val(int val, node_t* root) {  /* recursive find */  if(root != NULL){    if(val == root->val){        return TRUE;    }    else if (val < root->val){        return find_val(val, root->left);    }    else {        return find_val(val, root->right);    }  }  return FALSE;}/* * Given a pointer to the root, frees the memory associated with an entire tree. */void delete_bst(node_t* root) {  /* recursive delete */    if(root != NULL){        delete_bst(root->left);        delete_bst(root->right);        free(root);        root = NULL;    }    return;}/* Given a pointer to the root, prints all of the values in a tree. */void print_bst(node_t* root) {  if (root != NULL) {    printf("%d ", root->val);    print_bst(root->left);    print_bst(root->right);  }  return;}

测试文件：

test_bst.c

#include <assert.h>#include <stdio.h>#include "bst.h"int main() {  /* Insert 0. */  node_t* root = make_tree(1);  node_t* cur;  print_bst(root);  printf("\n");  assert(find_val(1, root) == TRUE);  /* Insert 1. */  cur = insert(0, root);  assert(find_val(0, root) == TRUE);  print_bst(root);  printf("\n");  /* Insert 2. */  cur = insert(2, root);  assert(find_val(2, root) == TRUE);  /* Print the tree. */  print_bst(root);  printf("\n");  /* Insert 4. */  cur = insert(4, root);  assert(find_val(4, root) == TRUE);  /* Insert 3 */  cur = insert(3, root);  assert(find_val(3, root) == TRUE);  print_bst(root);  printf("\n");    /* Delete the list. */  delete_bst(root);  return 0;}

测试结果：

输入命令:

$ gcc test_bst.c bst.c -o test

$ ./test