c语言加密和压缩，用霍夫曼算法

Question

问题遇到的现象和发生背景

用代码块功能插入代码，请勿粘贴截图

我的解答思路和尝试过的方法

我想要达到的

我想要一个加密和压缩的组件，并且只能使用stdio、stdlib、string 和math，和自己开发的库，用霍夫曼算法

Answer 1

参考如下

//#define _CRT_SECURE_NO_WARNINGS
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

struct head
{
    int b;                          //字符
    long count;                   //文件中该字符出现的次数
    long parent, lch, rch;        //make a tree
    char bits[256];               //the huffuman code
};

struct head header[512], tmp;  //节点树

void printfPercent(int per)
{
    int i = 0;
    printf("|");
    for(i = 0; i < 10; i++)
    {
        if(i < per/10)
            printf(">");
        else
            printf("-");
    }
    printf("|已完成%d%%\n",per);
}

//函数：compress()
//作用：读取文件内容并加以压缩
//将压缩内容写入另一个文档
int compress(const char *filename,const char *outputfile)
{
    char buf[512];
    unsigned char c;
    long i, j, m, n, f;
    long min1, pt1, flength;
    FILE *ifp, *ofp;
    int per = 10;
    ifp = fopen(filename, "rb");                  //打开原始文件
    if (ifp == NULL)
    {
        printf("打开文件失败:%s\n",filename);
        return 0;                             //如果打开失败，则输出错误信息
    }
    ofp = fopen(outputfile,"wb");                 //打开压缩后存储信息的文件
    if (ofp == NULL)
    {
        printf("打开文件失败:%s\n",outputfile);
        return 0;
    }
    flength = 0;
    while (!feof(ifp))
    {
        fread(&c, 1, 1, ifp);
        header[c].count ++;                       //读文件，统计字符出现次数
        flength ++;                               //记录文件的字符总数
    }
    flength --;
    header[c].count --;
    for (i = 0; i < 512; i ++)                    //HUFFMAN算法中初始节点的设置
    {
        if (header[i].count != 0)
            header[i].b = (unsigned char) i;
        else
            header[i].b = -1;
        header[i].parent = -1;
        header[i].lch = header[i].rch = -1;
    }

    for (i = 0; i < 256; i ++)                    //将节点按出现次数排序
    {
        for (j = i + 1; j < 256; j ++)
        {
            if (header[i].count < header[j].count)
            {
                tmp = header[i];
                header[i] = header[j];
                header[j] = tmp;
            }
        }
    }


    for (i = 0; i < 256; i ++)                    //统计不同字符的数量
    {
        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;
    }

    for (i = 0; i < n; i ++)                        //构造HUFFMAN树，设置字符的编码
    {
        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';
            }
        }
    }

    //下面的就是读原文件的每一个字符，按照设置好的编码替换文件中的字符
    fseek(ifp, 0, SEEK_SET);                                                //将指针定在文件起始位置
    fseek(ofp, 8, SEEK_SET);                                //以8位二进制数为单位进行读取
    buf[0] = 0;
    f = 0;
    pt1 = 8;

    printf("读取将要压缩的文件:%s\n",filename);
    printf("当前文件有:%d字符\n",flength);
    printf("正在压缩\n");

    while (!feof(ifp))
    {
        c = fgetc(ifp);
        f ++;
        for (i = 0; i < n; i ++)
        {
            if (c == header[i].b) break;
        }
        strcat(buf, header[i].bits);
        j = strlen(buf);
        c = 0;
        while (j >= 8)                                             //当剩余字符数量不小于8个时
        {
            for (i = 0; i < 8; i ++)                               //按照八位二进制数转化成十进制ASCII码写入文件一次进行压缩
            {
                if (buf[i] == '1') c = (c << 1) | 1;
                else c = c << 1;
            }
            fwrite(&c, 1, 1, ofp);
            pt1 ++;
            strcpy(buf, buf + 8);
            j = strlen(buf);
        }
        if(100 * f/flength > per)
        {
            printfPercent(per);
            per += 10;
        }
        if (f == flength)
            break;
    }
    printfPercent(100);

    if (j > 0)                                                      //当剩余字符数量少于8个时
    {
        strcat(buf, "00000000");
        for (i = 0; i < 8; i ++)
        {
            if (buf[i] == '1') c = (c << 1) | 1;
            else c = c << 1;                                        //对不足的位数进行补零
        }
        fwrite(&c, 1, 1, ofp);
        pt1 ++;
    }
    fseek(ofp, 0, SEEK_SET);                                        //将编码信息写入存储文件
    fwrite(&flength,1,sizeof(flength),ofp);
    fwrite(&pt1, sizeof(long), 1, ofp);
    fseek(ofp, pt1, SEEK_SET);
    fwrite(&n, sizeof(long), 1, ofp);
    for (i = 0; i < n; i ++)
    {
        tmp = header[i];

        fwrite(&(header[i].b), 1, 1, ofp);
        pt1++;
        c = strlen(header[i].bits);
        fwrite(&c, 1, 1, ofp);
        pt1++;
        j = strlen(header[i].bits);

        if (j % 8 != 0)                                             //当位数不满8时，对该数进行补零操作
        {
            for (f = j % 8; f < 8; f ++)
                strcat(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(header[i].bits, header[i].bits + 8);
            fwrite(&c, 1, 1, ofp);                                            //将所得的编码信息写入文件
            pt1++;
        }

        header[i] = tmp;
    }
    fclose(ifp);
    fclose(ofp);                                                              //关闭文件

    printf("压缩后文件为:%s\n",outputfile);
    printf("压缩后文件有:%d字符\n",pt1 + 4);

    return 1;                                       //返回压缩成功信息
}


//函数：uncompress()
//作用：解压缩文件，并将解压后的内容写入新文件
int uncompress(const char *filename,const char *outputfile)
{
    char buf[255], bx[255];
    unsigned char c;
    char out_filename[512];
    long i, j, m, n, f, p, l;
    long flength;
    int per = 10;
    int len = 0;
    FILE *ifp, *ofp;
    char c_name[512] = {0};
    ifp = fopen(filename, "rb");                                              //打开文件
    if (ifp == NULL)
    {
        return 0;     //若打开失败，则输出错误信息
    }

    //读取原文件长
    if(outputfile)
        strcpy(out_filename,outputfile);
    else
        strcpy(out_filename,c_name);

    ofp = fopen(out_filename, "wb");                                            //打开文件
    if (ofp == NULL)
    {
        return 0;
    }

    fseek(ifp,0,SEEK_END);
    len = ftell(ifp);
    fseek(ifp,0,SEEK_SET);

    printf("将要读取解压的文件:%s\n",filename);
    printf("当前文件有:%d字符\n",len);
    printf("正在解压\n");

    fread(&flength, sizeof(long), 1, ifp);                                    //读取原文件长
    fread(&f, sizeof(long), 1, ifp);
    fseek(ifp, f, SEEK_SET);
    fread(&n, sizeof(long), 1, ifp);                                          //读取原文件各参数
    for (i = 0; i < n; i ++)                                                  //读取压缩文件内容并转换成二进制码
    {
        fread(&header[i].b, 1, 1, ifp);
        fread(&c, 1, 1, ifp);
        p = (long) c;
        header[i].count = p;
        header[i].bits[0] = 0;
        if (p % 8 > 0) m = p / 8 + 1;
        else m = p / 8;
        for (j = 0; j < m; j ++)
        {
            fread(&c, 1 , 1 , ifp);
            f = c;
            _itoa(f, buf, 2);
            f = strlen(buf);
            for (l = 8; l > f; l --)
            {
                strcat(header[i].bits, "0");                                  //位数不足，执行补零操作
            }
            strcat(header[i].bits, buf);
        }
        header[i].bits[p] = 0;
    }

    for (i = 0; i < n; i ++)
    {
        for (j = i + 1; j < n; j ++)
        {
            if (strlen(header[i].bits) > strlen(header[j].bits))
            {
                tmp = header[i];
                header[i] = header[j];
                header[j] = tmp;
            }
        }
    }

    p = strlen(header[n-1].bits);
    fseek(ifp, 8, SEEK_SET);
    m = 0;
    bx[0] = 0;


    while (1)
    {
        while (strlen(bx) < (unsigned int)p)
        {
            fread(&c, 1, 1, ifp);
            f = c;
            _itoa(f, buf, 2);
            f = strlen(buf);
            for (l = 8; l > f; l --)
            {
                strcat(bx, "0");
            }
            strcat(bx, buf);
        }
        for (i = 0; i < n; i ++)
        {
            if (memcmp(header[i].bits, bx, header[i].count) == 0) break;
        }
        strcpy(bx, bx + header[i].count);
        c = header[i].b;
        fwrite(&c, 1, 1, ofp);
        m ++;

        if(100 *  m/flength > per)
        {
            printfPercent(per);
            per += 10;
        }
        if (m == flength) break;
    }
    printfPercent(100);

    fclose(ifp);
    fclose(ofp);

    printf("解压后文件为:%s\n",out_filename);
    printf("解压后文件有:%d字符\n",flength);

    return 1;                   //输出成功信息
}

int main(int argc,const char *argv[])
{
    memset(&header,0,sizeof(header));
    memset(&tmp,0,sizeof(tmp));

    compress("VS.zip","VS.zip.zip");//待压缩文件  
    uncompress("VS.zip.zip","VS-2.zip");//待解压文件 
    system("pause");

    return 0;
}
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