哈夫曼编码用C语言实现对常见文件（文档，音乐，视频，图像等）压缩与解压.zip

#include <stdio.h> #include <string.h> #include <stdlib.h> #include "Compress.h" int Compress(char *filename , char *extractfilename) { int i , j; int kinds = 0; int filelength = 0; unsigned char c; FILE *fp , *efp; Node node[256] , temp; int num; HuffmanNode *huffmantree; char codebuf[256]; int codelength; //初始化字符编码域,统计结点 /////////////////////////////////// for (i = 0; i < 256; ++i) { codebuf[i] = '\0'; } for (i = 0; i < 256; ++i) { node[i].ch = (unsigned char)i; node[i].count = 0; } /////////////////////////////////// //统计文件长度,字符频率 /////////////////////////////////// fp = fopen (filename , "rb"); if (fp == NULL) { return -1; } fread(&c , sizeof(unsigned char) , 1 , fp); while (!feof(fp)) { ++node[c].count; ++filelength; fread(&c , sizeof(unsigned char) , 1 , fp); } fclose(fp); /////////////////////////////////// //统计字符种类 /////////////////////////////////// for (i = 0; i < 255; ++i) { for (j = i + 1; j < 256; ++j) { if (node[i].count < node[j].count) { temp = node[i]; node[i] = node[j]; node[j] = temp; } } } for (i = 0; i < 256; ++i) { if (node[i].count) { ++kinds; } } /////////////////////////////////// if (1 == kinds) { //特殊情况(文件只含一种字符) /////////////////////////////////// efp = fopen(extractfilename , "wb"); fwrite (&kinds , sizeof(int) , 1 , efp); fwrite (&node[0].ch , sizeof(unsigned char) , 1 , efp); fwrite (&node[0].count , sizeof(int) , 1 , efp); fclose (efp); /////////////////////////////////// } else { //初始化顺序存储的哈夫曼结点 /////////////////////////////////// num = 2 * kinds - 1; huffmantree = (HuffmanNode*)malloc(num * sizeof(HuffmanNode)); for (i = 0; i < kinds; ++i) { huffmantree[i].ch = node[i].ch; huffmantree[i].count = node[i].count; huffmantree[i].parent = 0; huffmantree[i].leftchild = huffmantree[i].rightchild = -1; } for ( ;i < num; ++i) { huffmantree[i].parent = 0; huffmantree[i].leftchild = huffmantree[i].rightchild = -1; } /////////////////////////////////// //创建哈夫曼树 /////////////////////////////////// CreateHuffmanTree(huffmantree , kinds , num); /////////////////////////////////// //生成哈夫曼编码 /////////////////////////////////// HuffmanCode(huffmantree , kinds); /////////////////////////////////// //将字符种类,字符,频率,文件长度依次写入压缩文件前部分 /////////////////////////////////// efp = fopen (extractfilename , "wb"); fwrite (&kinds , sizeof(int) , 1 , efp); for (i = 0; i < kinds; ++i) { fwrite (&huffmantree[i].ch , sizeof(unsigned char) , 1 , efp); fwrite (&huffmantree[i].count , sizeof(int) , 1 , efp); } fwrite (&filelength , sizeof(int) , 1 , efp); /////////////////////////////////// //将字符编码写入压缩文件 /////////////////////////////////// fp = fopen (filename , "rb"); fread (&c , sizeof(unsigned char) , 1 , fp); while (!feof(fp)) { for (i = 0; i < kinds; ++i) { if (c == huffmantree[i].ch) { strcat(codebuf , huffmantree[i].code); } } while (strlen(codebuf) >= 8) { c = '\0'; for (i = 0; i < 8; ++i) { c <<= 1; if ('1' == codebuf[i]) { c |= 1; } } fwrite (&c , sizeof(unsigned char) , 1 , efp); strcpy(codebuf , codebuf + 8); } fread(&c , sizeof(unsigned char) , 1 , fp); } codelength = strlen(codebuf); if (codelength > 0) { c = '\0'; for (i = 0; i < codelength; ++i) { c <<= 1; if ('1' == codebuf[i]) { c |= 1; } } c <<= 8 - codelength; fwrite (&c , sizeof(unsigned char) , 1 , efp); } /////////////////////////////////// fclose (fp); fclose (efp); } free (huffmantree); }