hufftree.txt

别处下的一个huffman压缩程序

#include <stdio.h>
#include <stdlib.h>
#include "error.h"
#include "hufftree.h"
#include <string.h>
//Hufftree.c//

/* function prototypes */
void TraceHuffTree(HuffTree, char *);

/* creates a new HuffTree */
HuffTree NewHuffTree(char c, int f)
{
   HuffTree ht = malloc(sizeof(struct HuffNode));
   if(ht == NULL)
   {
      FatalError("Not enough memory!");
   }

   /* set the character and frequency fields in the HuffNode */
   ht->character = c;
	ht->frequency = f;
    left and right to NULL */
   ht->left = NULL;
   ht->right = NULL;

   return ht;
}

/* Creates a new HuffTree with left and right pointing to the two
   supplied HuffTrees */
HuffTree JoinHuffTrees(HuffTree q, HuffTree p)
{
   HuffTree new = malloc(sizeof(struct HuffNode));

   if(new == NULL)
   {
      FatalError("Not enough memory!");
   }

   /* since this tree doesn't carry any character information, just
      set character to NULL */
   new->character = '\0';
	new->frequency = (q->frequency + p->frequency);
    /* we want left to point to the smaller frequency */
   if(q->frequency < p->frequency)
   {
      new->left = q;
      new->right = p;
   }
   else if(q->frequency > p->frequency)
   {
      new->left = p;
      new->right = q;
   }
   else
   {
      new->left = q;
      new->right = p;
   }

   return new;
}

/* starts the output trace */
void OutputHuffCodes(HuffTree ht)
 char initial_code[2] = '\0';
   TraceHuffTree(ht,initial_code);
   return;
}

/* traces the HuffTree, setting the huffcode to 0 for left and 1 for
   right */
void TraceHuffTree(HuffTree ht,char *code)
{
   char left_code[MAX_ARRAY], right_code[MAX_ARRAY],
        special_char[MAX_ARRAY];
   int sw;

   sw = 0;

   if(ht->character == '\0')
   {
      /* this must be one of the "joined" HuffTrees */
      strcpy(left_code, code);
      strcpy(right_code, code);
      strcat(left_code, "0");
		strcat(right_code, "1");
       TraceHuffTree(ht->left, left_code);
   }
   else
   {
      /* this is not one of the "joined" HuffTrees, so output
         its character, along with the trace code we've encountered
         sofar to get here */
      if(ht->character == '\n')
      {
         strcpy(special_char, "nl");
         sw = 1;
      }
      else if(ht->character == ' ')
      {
         strcpy(special_char, "sp");
         sw = 1;
      }
      else if(ht->character == '\a')
      {
         strcpy(special_char, "bell");
         sw = 1;
		}
      }
      else if(ht->character == ' ')
      {
         strcpy(special_char, "sp");
         sw = 1;
      }
      else if(ht->character == '\a')
      {
         strcpy(special_char, "bell");
         sw = 1;
      }
      if(sw)
      {
         printf("%-6s%s\n",special_char,code);
      }
      else
      {
         printf("%-6c%s\n",ht->character,code);
      }
   }
   return;
}