#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>
#define _CRT_SECURE_NO_WARNINGS
/*哈夫曼树结构定义*/
struct head
{
unsigned char b; /*定义一个字符*/
long count; /*频率数据*/
long parent, lch, rch; /*创建哈夫曼树*/
char bits[256]; /*哈夫曼结点*/
}header[512], tmp;
/*压缩文件*/
void yasuo()
{
char filename[255], outputfile[255], buf[512];
unsigned char c;
char wenjianming[255];
long i, j, m, n, f;
long min1, pt1, flength;
FILE* ifp, * ofp;
printf("请输入文件地址及文件名：");
gets_s(filename);
ifp = fopen_s( &ifp,"filename", "rb"); /*打开源文件并读取*/
while (ifp == NULL)
{
printf("打开文件时出错！\n");
printf("请重新输入文件地址及文件名：");
gets_s(filename);
ifp = fopen_s(&ifp,"filename", "rb");
}
printf("请输入压缩后的文件地址和文件名及后缀：");
gets_s(wenjianming);
ofp = fopen_s(&ofp,"wenjianming", "wb"); /*创建并打开目的文件*/
while (ofp == NULL)
{
printf("请重新输入压缩后的文件地址和文件名及后缀：");
ofp = fopen_s(&ofp,"wenjianming", "wb");
}
flength = 0;
/*读取ifp文件*/
while (!feof(ifp))
{
fread(&c, 1, 1, ifp); /*按位读取文件*/
header[c].count++; /*记录文件的字符总数*/
flength++;
}
flength = -1;
header[c].count = -1; /*读取文件结束*/
/*构造哈弗曼树，初始结点的设置*/
for (i = 0; i < 512; i++)
{
if (header[i].count != 0)
header[i].b = (unsigned char)i;
else
header[i].b = 0;
header[i].parent = -1;
header[i].lch = header[i].rch = -1;
}
/*按结点出现的次数排序*/
for (i = 0; i < 256; i++)
{
for (j = i + 1; j < 256; j++)
{
if (header[i].count < header[j].count)
{
tmp = header[i];
header[i] = header[j];
header[j] = tmp;
}
}
}
/*统计不同字符的数量*/
for (i = 0; i < 256; i++)
if (header[i].count == 0)
break;
n = i;
m = 2 * n - 1;
for (i = n; i < m; i++)
{
min1 = 999999999;
for (j = 0; j < i; j++)
{
if (header[j].parent != -1)
continue;
if (min1 > header[j].count)
{
pt1 = j;
min1 = header[j].count;
continue;
}
}
header[i].count = header[pt1].count;
header[pt1].parent = i;
header[i].lch = pt1;
min1 = 999999999;
for (j = 0; j < i; j++)
{
if (header[j].parent != -1)
continue;
if (min1 > header[j].count)
{
pt1 = j;
min1 = header[j].count;
continue;
}
}
header[i].count += header[pt1].count;
header[i].rch = pt1;
header[pt1].parent = i;
}
/*构造哈夫曼树，设置字符编码*/
for (i = 0; i < n; i++)
{
f = i;
header[i].bits[0] = 0;
while (header[f].parent != -1)
{
j = f;
f = header[f].parent;
if (header[f].lch == j)
{
j = strlen(header[i].bits);
memmove(header[i].bits + 1, header[i].bits, j + 1);
header[i].bits[0] = '0';
}
else
{
j = strlen(header[i].bits);
memmove(header[i].bits + 1, header[i].bits, j + 1);
header[i].bits[0] = '1';
}
}
} /*哈弗曼构造结束*/
//读取源文件中的每一个字符，按照设置好的编码替换文件中的字符
fseek(ifp, 0, SEEK_SET); /*把文件指针指向文件的开头*/
fwrite(&flength, sizeof(int), 1, ofp); /*把哈弗曼代码写入ofp文件*/
fseek(ofp, 8, SEEK_SET); /*以8位二进制数为单位读取*/
buf[0] = 0;
f = 0;
pt1 = 8;
while (!feof(ifp))
{
c = fgetc(ifp); //从流中读取一个字符，并增加文件指针的位置
f++;
for (i = 0; i < n; i++)
{
if (c == header[i].b)
break;
}
strcat_s(buf, header[i].bits); //把header[i].bits所指字符串添加到buf结尾处
j = strlen(buf); //计算字符串buf的长度
c = 0;
while (j >= 8) /*按八位二进制数转化成十进制ASCII码写入文件一次进行压缩*/
{
for (i = 0; i < 8; i++)
{
if (buf[i] == '1') c = (c << 1) | 1;
else c = c << 1;
}
fwrite(&c, 1, 1, ofp);
pt1++;
strcpy_s(buf, buf + 8);
j = strlen(buf);
}
if (f == flength)
break;
}
if (j > 0) /*剩余字符数量少于8个*/
{
strcat_s(buf, "00000000");
for (i = 0; i < 8; i++)
{
if (buf[i] == '1') c = (c << 1) | 1;
else c = c << 1; /*对不足的位数补0*/
}
fwrite(&c, 1, 1, ofp);
pt1++;
}
//将编码信息写入存储文件
fseek(ofp, 4, SEEK_SET); /*fseek 用于二进制方式打开的文件,移动文件读写指针位置.第一个是文件流,第3个是指针零点位置,第2个是把指针移动到的地点. */
fwrite(&pt1, sizeof(long), 1, ofp); /*是要输出数据的地址,每次写入的位数,数据项的个数，目标文件地址*/
fseek(ofp, pt1, SEEK_SET);
fwrite(&n, sizeof(long), 1, ofp);
for (i = 0; i < n; i++)
{
fwrite(&(header[i].b), 1, 1, ofp);
c = strlen(header[i].bits);
fwrite(&c, 1, 1, ofp);
j = strlen(header[i].bits);
if (j % 8 != 0) /*按八位读取，位数不满8位时，对该位补0*/
{
for (f = j % 8; f < 8; f++)
strcat_s(header[i].bits, "0");
}
while (header[i].bits[0] != 0)
{
c = 0;
for (j = 0; j < 8; j++)
{
if (header[i].bits[j] == '1') c = (c << 1) | 1;
else c = c << 1;
}
strcpy_s(header[i].bits, header[i].bits + 8); /*把从header[i].bits+8地址开始且含有NULL结束符的字符串赋值到以header[i].bits开始的地址空间 */
fwrite(&c, 1, 1, ofp);
}
}
fclose(ifp);
fclose(ofp);
printf("压缩成功\n");
}
/*主函数*/
void main()
{
printf("输入a开始压缩\n");
printf("输入b结束压缩\n");
while (1)
{
char c;
c =_getch();
if (c == 'a')
yasuo();
else
{
if (c == 'b')
return;
}
}
}
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