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C语言实现哈夫曼编码

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本文实例为大家分享了C语言实现哈夫曼编码的具体代码,供大家参考,具体内容如下 。

代码来自于《小甲鱼C++快速入门》 。

主程序main.cpp 。

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#include "stdafx.h"
#include <stdlib.h>
#include "huffman.h"
int main()
{
  htTree *codeTree = buildTree( "I love wwwwwwwwwFishC.com!" ); //建立哈夫曼树
  hlTable *codeTable = buildTable(codeTree); //建立编码表
  encode(codeTable, "I love FishC.com!" ); //对输入的字符串进行编码
  decode(codeTree, "0011111000111" ); //解码
  system ( "pause" );
  return 0;
}

两个头文件: huffman.h:定义了哈夫曼树和编码表的结构 。

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#pragma once
#ifndef _HUFFMAN_H
#define _HUFFMAN_H
typedef struct _htNode{
  char symbol;
  struct _htNode *left,*right;
}htNode;
 
typedef struct _htTree{
  htNode *root;
}htTree;
 
typedef struct _hlNode{
  char symbol;
  char *code;
  struct _hlNode *next;
}hlNode;
 
typedef struct _hlTable{
  hlNode *first;
  hlNode *last;
}hlTable;
 
htTree *buildTree( char *str);
hlTable *buildTable(htTree *huffmanTree);
void encode(hlTable *table, char *stringToEncode);
void decode(htTree *tree, char *stringToDecode);
#endif

queue.h:定义了有序队列的结构,将字符按优先级排列,即频率从小到大排列,val是树节点,直接由队列建立起哈夫曼树 。

C语言实现哈夫曼编码

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#pragma once
#ifndef _PQUEUE_H
#define _PQUEUE_H
#include "huffman.h"
#define MAX_SZ 256
#define TYPE htNode *
 
typedef struct _pQueueNode{
  TYPE val;
  unsigned int priority;
  struct _pQueueNode *next;
}pQueueNode;
 
typedef struct _pQueue{
  unsigned int size;
  pQueueNode *first;
}pQueue;
 
void initPQueue(pQueue **queue);
void addPQueue(pQueue **queue, TYPE val, unsigned int priority);
TYPE getQueue(pQueue **queue);
#endif

两个cpp文件实现两个头文件声明的函数: huffman.cpp 。

  。

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#include "stdafx.h"
#include "queue.h"
#include "huffman.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
htTree *buildTree( char *str)
{
  int *probability = ( int *) malloc ( sizeof ( int ) * 256);
  //初始化
  for ( int i = 0; i < 256; i++)
  {
  probability[i] = 0;
  }
  //统计待编码的字符串各个字符出现的次数
  for ( int j = 0; str[j] != '\0' ; j++)
  {
  probability[str[j]]++;
  }
 
  //定义队列的头指针
  pQueue *huffmanQueue;
  initPQueue(&huffmanQueue);
  //填充队列
  for ( int k = 0; k < 256; k++)
  {
  if (probability[k] != 0)
  {
   htNode *aux = (htNode *) malloc ( sizeof (htNode));
   aux->left = NULL;
   aux->right = NULL;
   aux->symbol = ( char )k;
   addPQueue(&huffmanQueue, aux, probability[k]);
  }
  }
  free (probability);
  //生成哈夫曼树
  while (huffmanQueue->size != 1)
  {
  unsigned int newPriority = huffmanQueue->first->priority + huffmanQueue->first->next->priority;
  htNode *aux = (htNode *) malloc ( sizeof (htNode));
  aux->left = getQueue(&huffmanQueue);
  aux->right = getQueue(&huffmanQueue);
  addPQueue(&huffmanQueue, aux, newPriority);
  }
  htTree *tree = (htTree *) malloc ( sizeof (htTree));
  tree->root = getQueue(&huffmanQueue);
  return tree;
}
 
void traverseTree(htNode *treeNode,hlTable **table, int k, char code[256])
{
  if (treeNode->left == NULL&&treeNode->right == NULL)
  {
  code[k] = '\0' ;
  hlNode *aux = (hlNode *) malloc ( sizeof (hlNode));
  aux->code = ( char *) malloc ( sizeof ( char )*( strlen (code) + 1));
    strcpy (aux->code,code);
  aux->symbol = treeNode->symbol;
  aux->next = NULL;
  if ((*table)->first == NULL)
  {
   (*table)->first = aux;
   (*table)->last = aux;
  }
  else
  {
   (*table)->last->next = aux;
   (*table)->last = aux;
  }
  }
  if (treeNode->left != NULL)
  {
  code[k] = '0' ;
  traverseTree(treeNode->left,table,k+1,code);
  }
  if (treeNode->right != NULL)
  {
  code[k] = '1' ;
  traverseTree(treeNode->right, table, k + 1, code);
  }
}
 
hlTable *buildTable(htTree *huffmanTree)
{
  hlTable *table = (hlTable *) malloc ( sizeof (hlTable));
  table->first = NULL;
  table->last = NULL;
 
  char code[256];
  int k = 0;
 
  traverseTree(huffmanTree->root,&table,k,code);
  return table;
}
void encode(hlTable *table, char *stringToEncode)
{
  hlNode *traversal;
  printf ( "Encoding......\n\nInput string:\n%s\n\nEncoded string :\n" ,stringToEncode);
  for ( int i = 0; stringToEncode[i] != '\0' ; i++)
  {
  traversal = table->first;
  while (traversal->symbol != stringToEncode[i])
   traversal = traversal->next;
  printf ( "%s" , traversal->code);
  }
  printf ( "\n" );
}
void decode(htTree *tree, char *stringToDecode)
{
  htNode *traversal = tree->root;
 
  printf ( "\n\nDecoding......\n\nInput string: \n%s\n\nDecoded string: \n" ,stringToDecode);
  for ( int i = 0; stringToDecode[i] != '\0' ; i++)
  {
  if (traversal->left == NULL&&traversal->right == NULL)
  {
   printf ( "%c" , traversal->symbol);
   traversal = tree->root;
  }
  if (stringToDecode[i] == '0' )
   traversal = traversal->left;
  else if (stringToDecode[i] == '1' )
   traversal = traversal->right;
  else
  {
   printf ( "The input string is not coded correctly!\n" );
   return ;
  }
  }
  printf ( "\n\n" );
  return ;
}

queue.cpp:

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#include "stdafx.h"
#include <stdio.h>
#include <stdlib.h>
#include "queue.h"
void initPQueue(pQueue **queue)
{
  *queue = (pQueue *) malloc ( sizeof (pQueue));
  (*queue)->first = NULL;
  (*queue)->size = 0;
  return ;
}
void addPQueue(pQueue **queue, TYPE val, unsigned int priority)
{
  if ((*queue)->size == MAX_SZ)
  {
  printf ( "\n Queue is full. \n" );
  return ;
  }
  pQueueNode *aux = (pQueueNode *) malloc ( sizeof (pQueueNode));
  aux->priority = priority;
  aux->val = val;
  if ((*queue)->size == 0||(*queue)->first==NULL)
  {
  aux->next = NULL;
  (*queue)->first = aux;
  (*queue)->size = 1;
  return ;
  }
  else
  {
  if (priority <= (*queue)->first->priority)
  {
   aux->next = (*queue)->first;
   (*queue)->first = aux;
   (*queue)->size++;
   return ;
  }
  else
  {
   pQueueNode *iterator = (*queue)->first;
   while (iterator->next!=NULL)
   {
   if (priority <= iterator->next->priority)
   {
    aux->next = iterator->next;
    iterator->next = aux;
    (*queue)->size++;
    return ;
   }
   iterator = iterator->next;
   }
   if (iterator->next == NULL)
   {
   aux->next = NULL;
   iterator->next = aux;
   (*queue)->size++;
   return ;
   }
  }
  }
}
TYPE getQueue(pQueue **queue)
{
  TYPE returnValue;
  if ((*queue)->size > 0)
  {
  returnValue = (*queue)->first->val;
  (*queue)->first = (*queue)->first->next;
  (*queue)->size--;
  }
  else
  {
  returnValue = NULL;
  printf ( "\n Queue is empty \n" );
  }
 
  return returnValue;
}

运行结果:

C语言实现哈夫曼编码

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原文链接:https://blog.csdn.net/u011643312/article/details/53983278 。

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