C Primer+Plus（十七）高级数据表示 编程练习(二）

7、编写一个程序，能打开、读入一个文本文件并统计文件中每个单词出现的次数。用改进的二叉搜索树存储单词及其出现的次数。程序读入文件后，会提供一个有三个选项的菜单。第一个选项为列出所有单词连同其出现的次数。第二个选项为让您输入一个单词，程序报告该单词在文件中出现的次数。第三个选项为退出。

断断续续编写代码、测试，花了差不多两天时间，总算告成。

*建立该问题的二叉树节点模型

//BST Model--START------------------
typedef struct node
{
    char word[15];
    int times;        //出现的次数
    struct node *left;
    struct node *right;
}Node;

typedef struct tree
{
   Node *root;
   int num;      //树中单词数
}Tree;
//BST Model--FINISH--------------------

*研究本题需求，实现接口代码

//BST function START-----------------------------
//初始化树
void IniTree(Tree *ptree)
{
    ptree->root=NULL;
    ptree->num=0;
}


//查找树中有无指定单词
//若未找到，返回NULL；若找到返回指定项目所在节点地址
Node *FindWord(char word[15],const Node *root)
{
   Node *pnode;
   pnode=root;
   if(root==NULL)
   {
      return NULL;
   }
   while(strcmp(word,pnode->word)!=0 && (pnode!=NULL))
   {  
      if(strcmp(word,pnode->word)<0)
         pnode=pnode->left;
      else
         pnode=pnode->right;
   }
   return pnode;
}


//添加单词节点
//通过FindWord做支撑，若存在，则相应节点次数+1
//若不存在，则找到合适的空位，同时定位该空位的父节点
//创建该单词的节点，并判断在空位父节点的左还是右，然后添加
void AddWord(char word[15],Tree *ptree)
{
   Node *pnode,*newnode,*fathernode;
   pnode=FindWord(word,ptree->root);
   if(pnode!=NULL)
   {     pnode->times++;
   }
   else
   {
      newnode=ptree->root;
      while(newnode!=NULL)     //找空位，并且定位空位的父节点
     {
         if(strcmp(word,newnode->word)<0)
         {
              fathernode=newnode;      
              newnode=newnode->left;
         }
         else
         {
              fathernode=newnode;      
              newnode=newnode->right;
         }
      } 
      newnode=(Node*)malloc(sizeof(Node));
      newnode->left=NULL;
      newnode->right=NULL;
      newnode->times=1;
      strcpy(newnode->word,word);   //设置节点信息
       
  if(ptree->root==NULL)  //如果树为空
  {
      ptree->root=newnode;
      ptree->num++; 
   }
   else
   {
      if(strcmp(word,fathernode->word)<0)   //说明父节点左子节点为空
       {    
          fathernode->left=newnode;
          ptree->num++;
      }
      else
      {    
         fathernode->right=newnode;
         ptree->num++;
      }
    }
  }
}



//打印树中单词信息
void PrintTree(const Node *root)
{
   if(root!=NULL)
   {  PrintTree(root->left);
      printf("the word is %s,its times is %d.\n",root->word,root->times);
      PrintTree(root->right);
   }
}


//输入单词，显示次数
void showtimes(const Tree *ptree)
{
   Node *pnode;
   char word[15];
   printf("input the word.\n");
   gets(word);
   pnode=FindWord(word,ptree->root);
   if(pnode==NULL)
     printf("the word:%s is not in the tree.\n",word);
   else
     printf("the word:%s times in tree is:%d.\n",word,pnode->times);
 }
//BST function FINISH---------------

 

*完整代码：

#include
#include<string.h>
#include

//BST Model--START------------------
typedef struct node
{
    char word[15];
    int times;        
struct node *left;
    struct node *right;
}Node;

typedef struct tree
{
   Node *root;
   int num;      
}Tree;
//BST Model--FINISH--------------------



//BST function START-----------------------------
//初始化树
void IniTree(Tree *ptree)
{
    ptree->root=NULL;
    ptree->num=0;
}


//查找树中有无指定单词
Node *FindWord(char word[15],const Node *root)
{
   Node *pnode;
   pnode=root;
   if(root==NULL)
   {
      return NULL;
   }
   while(strcmp(word,pnode->word)!=0 && (pnode!=NULL))
   {  
      if(strcmp(word,pnode->word)<0)
         pnode=pnode->left;
      else
         pnode=pnode->right;
   }
   return pnode;
}


//添加单词节点
void AddWord(char word[15],Tree *ptree)
{
   Node *pnode,*newnode,*fathernode;
   pnode=FindWord(word,ptree->root);
   if(pnode!=NULL)
   {     pnode->times++;
   }
   else
   {
      newnode=ptree->root;
      while(newnode!=NULL)     
      {
         if(strcmp(word,newnode->word)<0)
         {
              fathernode=newnode;      
              newnode=newnode->left;
         }
     else
         {
              fathernode=newnode;      
              newnode=newnode->right;
         }
      } 
      newnode=(Node*)malloc(sizeof(Node));
      newnode->left=NULL;
      newnode->right=NULL;
      newnode->times=1;
      strcpy(newnode->word,word);   
if(ptree->root==NULL)  
      {
           ptree->root=newnode;
           ptree->num++; 
      }
      else
      {
         if(strcmp(word,fathernode->word)<0)   
          {    
        fathernode->left=newnode;
        ptree->num++;
         }
         else
         {    
        fathernode->right=newnode;
        ptree->num++;
     }
       }
     }
}



//打印树中单词信息
void PrintTree(const Node *root)
{
   if(root!=NULL)
   {  PrintTree(root->left);
      printf("the word is %s,its times is %d.\n",root->word,root->times);
      PrintTree(root->right);
   }
}


//输入单词，显示次数
void showtimes(const Tree *ptree)
{
   Node *pnode;
   char word[15];
   printf("input the word.\n");
   gets(word);
   pnode=FindWord(word,ptree->root);
   if(pnode==NULL)
     printf("the word:%s is not in the tree.\n",word);
   else
     printf("the word:%s times in tree is:%d.\n",word,pnode->times);
 }
//BST function FINISH---------------

int main()
{
  FILE *fp;
  Tree *wordtree;
  Node *new_node;
  char newword[15];
  char ch,cc;
  int i=0;
//读入文件，创建单词的二叉搜索树-----------------------
  fp=fopen("ab.txt","r");
  if(fp==NULL)
  {
      fprintf(stdout,"can't open the file.\n");
      getch();
      exit(1);
  }
//初始化树
  IniTree(wordtree);

//读入文件字符
  while((ch=getc(fp))!=EOF)
  {
    if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
    {
    newword[i]=ch;
        i++;
    }
    else
    {
        if(i==0)             
continue;
        else                 
        {
        newword[i]='\0';
       AddWord(newword,wordtree);  //加入单词树
       i=0;
        }
     }
   }
//针对文本最后字符为字母，则还未设置字符串结束符就跳出while循环了
//增加本段代码处理
   if(i!=0)
   {
       newword[i]='\0';
       AddWord(newword,wordtree);  //加入单词树
   }  
   
//单词二叉搜索树创建完成---------------------------------------------------------    


   printf("-----Please choose--------\n");
   printf("a:---show all words-------\n");
   printf("b:---some word------------\n");
   printf("c:---Quit-----------------\n");

   while((cc=getch())!='c')
   {switch(cc)
      {
       case 'a':PrintTree(wordtree->root);break;
       case 'b':showtimes(wordtree);break;
      }
      printf("-----Please choose--------\n");
      printf("a:---show all words-------\n");
      printf("b:---some word------------\n");
      printf("c:---Quit-----------------\n");

    }

    fclose(fp);
    return 0;
}

 

转载于:https://www.cnblogs.com/tsembrace/p/3194344.html