数据结构实验四-赫夫曼编码

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//////////////////////////////////////////////////////////////////////////////
/*定义赫夫曼树结点的结构体变量，存放结点的权值、字符、双亲、坐孩子和右孩子*/
typedef struct{
int weight;
char ch;                 //增加一个域用于存放该节点的字符
int parent, lchild, rchild;
}HTNode, *HuffmanTree;
typedef char **HuffmanCode; //指向赫夫曼编码的指针
//////////////////////////////////////////////////////////////////////////////
/*本程序用到的函数原型*/
void welcome();    //打印操作选择界面
void HuffmanCoding(HuffmanTree &, char *, int *, int);//建立赫夫曼树的算法
void select(HuffmanTree HT, int j, int *s1, int *s2); //从目前已建好的赫夫曼树中选择parent为0且weight最小的两个结点
void Init(); //输入n个字符及其对应的权值，根据权值建立哈夫曼树
void Coding(); //编码
void Decoding(); //译码
void Print_code(); //打印译码好的代码文件
void Print_tree(); //以凹凸表形式打印哈夫曼树
int Read_tree(HuffmanTree &HT); //从文件中读入赫夫曼树
void find(HuffmanTree &HT, char *code, char *text, int i, int m);//译码时根据01字符串寻找相应叶子节点的递归算法
void Convert_tree(unsigned char T[100][100], int s, int *i, int j);//将内存中的赫夫曼树转换成凹凸表形式的赫夫曼树
HuffmanTree HT; //全局变量，指向存放赫夫曼树的存储空间
int n = 0; //全局变量，存放赫夫曼树叶子结点的数目
int main()
{
char select;
while (1)
{
welcome();
scanf("%c", &select);
switch (select)
{
case 'i':
case 'I':Init(); break;
case 'c':
case 'C':Coding(); break;
case 'd':
case 'D':Decoding(); break;
case 'p':
case 'P':Print_code(); break;
case 't':
case 'T':Print_tree(); break;
case 'e':
case 'E':exit(1);
default:printf("Input error!\n");
}
getchar();
}
return 0;
}
void welcome() //打印操作选择界面
{
printf("*-----------------------------------------------------*\n");
printf("|                What do you want to do?              |\n");
printf("|-----------------------------------------------------|\n");
printf("|                                                     |\n");
printf("| I--------------------------Init the Huffman tree. |\n");
printf("| C--------------------------Code your file.         |\n");
printf("| D--------------------------Decode the code.        |\n");
printf("| P--------------------------Print the codefile.     |\n");
printf("| T--------------------------Print the Huffman tree. |\n");
printf("|                                                     |\n");
printf("*-----------------------------------------------------*\n");
}
//////////////////////////////////////////////////////////////////////////////////////
/*初始化函数，输入n个字符及其对应的权值，根据权值建立哈夫曼树，并将其存于文件hfmtree中*/
void Init()
{
FILE *fp;
int i, n, w[52]; //w数组存放n个字符的权值
char character[52]; //存放n个字符
printf("\n输入字符个数 n:");
scanf("%d", &n);        //输入字符集大小
printf("输入%d个字符及其对应的权值:\n", n);
for (i = 0; i < n; i++)
{
char b = getchar();
scanf("%c", &character[i]);
scanf("%d", &w[i]);           //输入n个字符和对应的权值
}
HuffmanCoding(HT, character, w, n);    //建立赫夫曼树
if ((fp = fopen("hfmtree.txt", "w")) == NULL)
printf("Open file hfmtree.txt error!\n");
for (i = 1; i <= 2 * n - 1; i++)
{
if (fwrite(&HT[i], sizeof(HTNode), 1, fp) != 1)   //将建立的赫夫曼树存入文件hfmtree.txt中
printf("File write error!\n");
}
printf("\n建立赫夫曼树成功，已将其存于文件hfmtree.txt中\n");
fclose(fp);
}
///////////////////////////////////////////////////////////////////////////////////
//////建立赫夫曼树的算法///////////////////////////////////////////////////////////
void HuffmanCoding(HuffmanTree &HT, char *character, int *w, int n)
{
int m, i, s1, s2;
HuffmanTree p;
if (n <= 1) return;
m = 2 * n - 1;
HT = (HuffmanTree) malloc((m + 1)*sizeof(HTNode));
for (p = HT + 1, i = 1; i <= n; ++i, ++p, ++character, ++w)
{
p->ch = *character;
p->weight = *w;
p->parent = 0;
p->lchild = 0;
p->rchild = 0;
}
for (; i <= m; ++i, ++p)
{
p->ch = 0;
p->weight = 0;
p->parent = 0;
p->lchild = 0;
p->rchild = 0; }
for (i = n + 1; i <= m; ++i)
{
select(HT, i - 1, &s1, &s2);
HT[s1].parent = i;
HT[s2].parent = i;
HT[i].lchild = s1;
HT[i].rchild = s2;
HT[i].weight = HT[s1].weight + HT[s2].weight;
}
}
///////////////////////////////////////////////////////////////////////////////
/*从HT[1]到HT[j]中选择parent为0且weight最小的两个结点，用s1和s2返回其序号*/
void select(HuffmanTree HT, int j, int *s1, int *s2)
{
int i;
//找weight最小的结点
for (i = 1; i <= j; i++)
if (HT[i].parent == 0)
{
*s1 = i;
break;
}
for (; i <= j; i++)
if ((HT[i].parent == 0) && (HT[i].weight < HT[*s1].weight))
*s1 = i;
HT[*s1].parent = 1;
//找weight次小的结点
for (i = 1; i <= j; i++)
if (HT[i].parent == 0)
{
*s2 = i; break;
}
for (; i <= j; i++)
if ((HT[i].parent == 0) && (i != *s1) && (HT[i].weight < HT[*s2].weight))
*s2 = i;
}
///////////////////////////////////////////////////////////////////////////////
/*对文件tobetrans中的正文进行编码，然后将结果存入文件codefile中*/
void Coding()
{
FILE *fp, *fw;
int i, f, c, start;
char *cd;
HuffmanCode HC;
if (n == 0)
n = Read_tree(HT);//从文件hfmtree.txt中读入赫夫曼树,返回叶子结点数
/////以下程序段求赫夫曼树中各叶子节点的字符对应的的编码，并存于HC指向的空间中
{
HC = (HuffmanCode) malloc((n + 1)*sizeof(char*) );
cd = (char *) malloc(n*sizeof(char) );
cd[n - 1] = '\0';
for (i = 1; i <= n; ++i)
{
start = n - 1;
for (c = i, f = HT[i].parent; f != 0; c = f, f = HT[f].parent)
if (HT[f].lchild == c)
cd[--start] = '0';
else cd[--start] = '1';
HC[i] = (char *) malloc((n - start)*sizeof(char) );
strcpy(HC[i], &cd[start]);
}
free(cd);
}
/////////////////////////////////////////////////////////////////////////////////////
if ((fp = fopen("tobetrans.txt", "rb")) == NULL)
printf("Open file tobetrans.txt error!\n");
if ((fw = fopen("codefile.txt", "wb+")) == NULL)
printf("Open file codefile.txt error!\n");
char temp;
fscanf(fp, "%c", &temp); //从文件读入第一个字符
while (!feof(fp))
{
for (i = 1; i <= n; i++)
if (HT[i].ch == temp) break;    //在赫夫曼树中查找字符所在的位置
for (int r = 0; HC[i][r] != '\0'; r++) //将字符对应的编码存入文件
fputc(HC[i][r], fw);
fscanf(fp, "%c", &temp);        //从文件读入下一个字符
}
fclose(fw);
fclose(fp);
printf("\n对文件hfmtree.txt编码成功,结果已存入codefile.txt中。\n\n");
}

/////////////////////////////////////////////////////////////////////////
/*将文件codefile中的代码进行译码，结果存入文件textfile中*/
void Decoding()
{
FILE *fp, *fw;
int m, i;
char *code, *text, *p;
if (n == 0)
n = Read_tree(HT);//从文件hfmtree.txt中读入赫夫曼树,返回叶子结点数
if ((fp = fopen("codefile.txt", "rb")) == NULL)
printf("Open file codefile.txt error!\n");
if ((fw = fopen("textfile.txt", "wb+")) == NULL)
printf("Open file textfile.txt error!\n");
code = (char *) malloc(sizeof(char) );
fscanf(fp, "%c", code);        //从文件读入一个字符
for (i = 1; !feof(fp); i++)
{
code = (char *) realloc(code, (i + 1)*sizeof(char) ); //增加空间
fscanf(fp, "%c", &code[i]);     //从文件读入下一个字符
}
code[i - 1] = '\0';
/////////到此codefile.txt文件中的字符已全部读入，存放在code数组中
text = (char *) malloc(100 * sizeof(char) );
p = text;
m = 2 * n - 1;
if (*code == '0')
find(HT, code, text, HT[m].lchild, m);   //从根节点的左子树去找
else
find(HT, code, text, HT[m].rchild, m);   //从根节点的右子树去找
for (i = 0; p[i] != '\0'; i++) //把译码好的字符存入文件textfile.txt中
fputc(p[i], fw);
fclose(fp);
fclose(fw);
printf("\n对codefile.txt文件译码成功，结果已存入textfile.txt文件。\n\n");
}
//////////////////////////////////////////////////////////////////////////////////////////////////////
/*将文件codefi1e以紧凑格式显示在终端上,每行50个代码。同时将此字符形式的编码文件写入文件codeprint中。*/
void Print_code()
{
FILE *fp, *fw;
char temp;
int i;
if ((fp = fopen("codefile.txt", "rb")) == NULL)
printf("Open file codefile.txt error!\n");
if ((fw = fopen("codeprint.txt", "wb+")) == NULL)
printf("Open file codeprint.txt error!\n");
printf("\n文件codefi1e以紧凑格式显示如下:\n");
fscanf(fp, "%c", &temp);        //从文件读入一个字符
for (i = 1; !feof(fp); i++)
{
printf("%c", temp);
if (i % 50 == 0) printf("\n");
fputc(temp, fw);   //将该字符存入文件codeprint.txt中
fscanf(fp, "%c", &temp);        //从文件读入一个字符
}
printf("\n\n此字符形式的编码已写入文件codeprint.txt中.\n\n");
fclose(fp);
fclose(fw);
}
//////////////////////////////////////////////////////////////////////////////////////////////////
/*将已在内存中的哈夫曼树以凹凸表形式显示在屏幕上，同时将此字符形式的哈夫曼树写入文件treeprint中。*/
void Print_tree()
{
unsigned char T[100][100];
int i, j, m = 0;
FILE *fp;
if (n == 0)
n = Read_tree(HT);//从文件hfmtree.txt中读入赫夫曼树,返回叶子结点数

Convert_tree(T, 0, &m, 2 * n - 1); //将内存中的赫夫曼树转换成凹凸表形式的树，存于数组T中
if ((fp = fopen("treeprint.txt", "wb+")) == NULL)
printf("Open file treeprint.txt error!\n");
printf("\n以凹凸表形式打印已建好的赫夫曼树：\n");
for (i = 1; i <= 2 * n - 1; i++)
{
for (j = 0; T[i][j] != 0; j++)
{
if (T[i][j] == ' ') { printf(" "); fputc(T[i][j], fp); }
else
{
printf("%d", T[i][j]); fprintf(fp, "%d\n", T[i][j]);
}
}
printf("\n");
}
fclose(fp);
printf("\n此字符形式的哈夫曼树已写入文件treeprint.txt中.\n\n");

}
//////////////////////////////////////////////////////////////////////////////////
/*从文件hfmtree.txt中读入赫夫曼树，返回叶子节点数*/
int Read_tree(HuffmanTree &HT)
{
FILE *fp;
int i, n;
HT = (HuffmanTree) malloc(sizeof(HTNode));
if ((fp = fopen("hfmtree.txt", "r")) == NULL)
printf("Open file hfmtree.txt error!\n");
for (i = 1; !feof(fp); i++)
{
HT = (HuffmanTree) realloc(HT, (i + 1)*sizeof(HTNode)); //增加空间
fread(&HT[i], sizeof(HTNode), 1, fp); //读入一个节点信息
}
fclose(fp);
n = (i - 1) / 2;
return n;
}
////////////////////////////////////////////////////////////////
/*译码时根据01字符串寻找相应叶子节点的递归算法*/
void find(HuffmanTree &HT, char *code, char *text, int i, int m)
{

if (*code != '\0') //若译码未结束
{
code++;
if (HT[i].lchild == 0 && HT[i].rchild == 0)   //若找到叶子节点
{
*text = HT[i].ch; //将叶子节点的字符存入text中
text++;
if ((*code == '0'))
find(HT, code, text, HT[m].lchild, m); //继续从根节点的左子树找
else
find(HT, code, text, HT[m].rchild, m); //继续从根节点的右子树找
}
else   //如果不是叶子节点
if (*code == '0')
find(HT, code, text, HT[i].lchild, m);   //从该节点的左子树去找
else
find(HT, code, text, HT[i].rch

------------------ild, m);   //从该节点的右子树去找

}
else
*text = '\0'; //译码结束
}
////////////////////////////////////////////////////////////////////////
/*将内存中的赫夫曼树转换成凹凸表形式的赫夫曼树*/
void Convert_tree(unsigned char T[100][100], int s, int *i, int j)
{
int k, l;
l = ++(*i);
for (k = 0; k < s; k++)
T[l][k] = ' ';
T[l][k] = HT[j].weight;
if (HT[j].lchild)
Convert_tree(T, s + 1, i, HT[j].lchild);
if (HT[j].rchild)
Convert_tree(T, s + 1, i, HT[j].rchild);
T[l][++k] = '\0';
}