哈夫曼编码实验报告

数据结构实验班级:网络工程二班姓名:田恒韬学号:2220121766一．实验目的利用哈夫曼编码进行通信可以大大提高信道利用率，缩短信息传输时间，降低传输成本。

但是，这要求在发送端通过一个编码系统对待传数据预先编码，在接收端将传来的数据进行译码（复原）。

对于双工信道（即可以双向传输信息的信道），每端都需要一个完整的编码/译码系统。

试为这样的信息收发站写一个哈夫曼编码的编码/译码器。

源程序#include <iostream.h>#include <iomanip.h>#include <string.h>#include <malloc.h>#include <stdio.h>//typedef int TElemType;const int UINT_MAX=1000;char str[50];typedef struct{int weight,K;int parent,lchild,rchild;}HTNode,* HuffmanTree;typedef char **HuffmanCode;//-----------全局变量-----------------------HuffmanTree HT;HuffmanCode HC;int w[50],i,j,n;char z[50];int flag=0;int numb=0;// -----------------求哈夫曼编码-----------------------struct cou{char data;int count;}cou[50];int min(HuffmanTree t,int i){ // 函数void select()调用int j,flag;int k=UINT_MAX; // 取k为不小于可能的值,即k为最大的权值1000 for(j=1;j<=i;j++)if(t[j].weight<k&&t[j].parent==0)k=t[j].weight,flag=j;t[flag].parent=1;return flag;}//--------------------slect函数----------------------void select(HuffmanTree t,int i,int &s1,int &s2){ // s1为最小的两个值中序号小的那个int j;s1=min(t,i);s2=min(t,i);if(s1>s2){j=s1;s1=s2;s2=j;}}void HuffmanCoding(HuffmanTree &HT,HuffmanCode &HC,int *w,int n) { // w存放n个字符的权值(均>0),构造哈夫曼树HT,并求出n个字符的哈夫曼编码HCint m,i,s1,s2,start;//unsigned c,f;int c,f;HuffmanTree p;char *cd;if(n<=1)return;//检测结点数是否可以构成树m=2*n-1;HT=(HuffmanTree)malloc((m+1)*sizeof(HTNode)); // 0号单元未用 for(p=HT+1,i=1;i<=n;++i,++p,++w){p->weight=*w;p->parent=0;p->lchild=0;p->rchild=0;}for(;i<=m;++i,++p)p->parent=0;for(i=n+1;i<=m;++i) // 建哈夫曼树{ // 在HT[1~i-1]中选择parent为0且weight最小的两个结点,其序号分别为s1和s2select(HT,i-1,s1,s2);HT[s1].parent=HT[s2].parent=i;HT[i].lchild=s1;HT[i].rchild=s2;HT[i].weight=HT[s1].weight+HT[s2].weight;}// 从叶子到根逆向求每个字符的哈夫曼编码HC=(HuffmanCode)malloc((n+1)*sizeof(char*));// 分配n个字符编码的头指针向量([0]不用)cd=(char*)malloc(n*sizeof(char)); // 分配求编码的工作空间cd[n-1]='\0'; // 编码结束符for(i=1;i<=n;i++){ // 逐个字符求哈夫曼编码start=n-1; // 编码结束符位置for(c=i,f=HT[i].parent;f!=0;c=f,f=HT[f].parent)// 从叶子到根逆向求编码if(HT[f].lchild==c)cd[--start]='0';elsecd[--start]='1';HC[i]=(char*)malloc((n-start)*sizeof(char)); // 为第i个字符编码分配空间strcpy(HC[i],&cd[start]); // 从cd复制编码(串)到HC }free(cd); // 释放工作空间}//--------------------- 获取报文并写入文件---------------------------------int InputCode(){//cout<<"请输入你想要编码的字符"<<endl;FILE *tobetran;if((tobetran=fopen("tobetran.txt","w"))==NULL){cout<<"不能打开文件"<<endl;return 0;}cout<<"请输入你想要编码的字符"<<endl;gets(str);fputs(str,tobetran);cout<<"获取报文成功"<<endl;fclose(tobetran);return strlen(str);}//--------------初始化哈夫曼链表--------------------------------- void Initialization(){ int a,k,flag,len;a=0;len=InputCode();for(i=0;i<len;i++){k=0;flag=1;cou[i-a].data=str[i];cou[i-a].count=1;while(i>k){if(str[i]==str[k]){a++;flag=0;}k++;if(flag==0)break;}if(flag){for(j=i+1;j<len;j++){if(str[i]==str[j])++cou[i-a].count;}}}n=len-a;for(i=0;i<n;i++){ cout<<cou[i].data<<" ";cout<<cou[i].count<<endl;}for(i=0;i<=n;i++){*(z+i)=cou[i].data;*(w+i)=cou[i].count;}HuffmanCoding(HT,HC,w,n);//------------------------ 打印编码-------------------------------------------cout<<"字符对应的编码为:"<<endl;for(i=1;i<=n;i++){puts(HC[i]);}//-------------------------- 将哈夫曼编码写入文件------------------------cout<<"下面将哈夫曼编码写入文件"<<endl<<"...................."<<endl;FILE *htmTree;char r[]={' ','\0'};if((htmTree=fopen("htmTree.txt","w"))==NULL){cout<<"can not open file"<<endl;return;}fputs(z,htmTree);for(i=0;i<n+1;i++){fprintf(htmTree,"%6d",*(w+i));fputs(r,htmTree);}for(i=1;i<=n;i++){fputs(HC[i],htmTree);fputs(r,htmTree);}fclose(htmTree);cout<<"已将字符与对应编码写入根目录下文件htmTree.txt中"<<endl<<endl;}//---------------------编码函数--------------------------------- void Encoding(){cout<<"下面对目录下文件tobetran.txt中的字符进行编码"<<endl; FILE *tobetran,*codefile;if((tobetran=fopen("tobetran.txt","rb"))==NULL){cout<<"不能打开文件"<<endl;}if((codefile=fopen("codefile.txt","wb"))==NULL){cout<<"不能打开文件"<<endl;}char *tran;i=99;tran=(char*)malloc(100*sizeof(char));while(i==99){if(fgets(tran,100,tobetran)==NULL){cout<<"不能打开文件"<<endl;break;}for(i=0;*(tran+i)!='\0';i++){for(j=0;j<=n;j++){if(*(z+j-1)==*(tran+i)){fputs(HC[j],codefile);if(j>n){cout<<"字符错误，无法编码!"<<endl; break;}}}}}cout<<"编码工作完成"<<endl<<"编码写入目录下的codefile.txt中"<<endl<<endl;fclose(tobetran);fclose(codefile);free(tran);}//-----------------译码函数---------------------------------void Decoding(){cout<<"下面对根目录下文件codefile.txt中的字符进行译码"<<endl;FILE *codef,*txtfile;if((txtfile=fopen("txtfile.txt","w"))==NULL){cout<<"不能打开文件"<<endl;}if ((codef=fopen("codefile.txt","r"))==NULL){cout<<"不能打开文件"<<endl;}char *work,*work2,i2;int i4=0,i,i3;unsigned long length=10000;work=(char*)malloc(length*sizeof(char));fgets(work,length,codef);work2=(char*)malloc(length*sizeof(char));i3=2*n-1;for(i=0;*(work+i-1)!='\0';i++){i2=*(work+i);if(HT[i3].lchild==0){*(work2+i4)=*(z+i3-1);i4++;i3=2*n-1;i--;}else if(i2=='0') i3=HT[i3].lchild;else if(i2=='1') i3=HT[i3].rchild;}*(work2+i4)='\0';fputs(work2,txtfile);cout<<"译码完成"<<endl<<"内容写入根目录下的文件txtfile.txt中"<<endl<<endl;free(work);free(work2);fclose(txtfile);fclose(codef);}//-----------------------打印编码的函数----------------------void Code_printing(){cout<<"下面打印根目录下文件CodePrin.txt中编码字符"<<endl; FILE * CodePrin,* codefile;if((CodePrin=fopen("CodePrin.txt","w"))==NULL){cout<<"不能打开文件"<<endl;return;}if((codefile=fopen("codefile.txt","r"))==NULL){cout<<"不能打开文件"<<endl;return;}char *work3;work3=(char*)malloc(51*sizeof(char));do{if(fgets(work3,51,codefile)==NULL){cout<<"不能读取文件"<<endl;break;}fputs(work3,CodePrin);puts(work3);}while(strlen(work3)==50);free(work3);cout<<"打印工作结束"<<endl<<endl;fclose(CodePrin);fclose(codefile);}//------------------------------- 打印译码函数---------------------------------------------void Code_printing1(){cout<<"下面打印根目录下文件txtfile.txt中译码字符"<<endl;FILE * CodePrin1,* txtfile;if((CodePrin1=fopen("CodePrin1.txt","w"))==NULL){cout<<"不能打开文件"<<endl;return;}if((txtfile=fopen("txtfile.txt","r"))==NULL){cout<<"不能打开文件"<<endl;return;}char *work5;work5=(char*)malloc(51*sizeof(char));do{if(fgets(work5,51,txtfile)==NULL){cout<<"不能读取文件"<<endl;break;}fputs(work5,CodePrin1);puts(work5);}while(strlen(work5)==50);free(work5);cout<<"打印工作结束"<<endl<<endl;fclose(CodePrin1);fclose(txtfile);}//------------------------打印哈夫曼树的函数-----------------------void coprint(HuffmanTree start,HuffmanTree HT){if(start!=HT){FILE * TreePrint;if((TreePrint=fopen("TreePrint.txt","a"))==NULL){cout<<"创建文件失败"<<endl;return;}numb++;//该变量为已被声明为全局变量coprint(HT+start->rchild,HT);cout<<setw(5*numb)<<start->weight<<endl;fprintf(TreePrint,"%d\n",start->weight);coprint(HT+start->lchild,HT);numb--;fclose(TreePrint);}}void Tree_printing(HuffmanTree HT,int w){HuffmanTree p;p=HT+w;cout<<"下面打印哈夫曼树"<<endl;coprint(p,HT);cout<<"打印工作结束"<<endl;}//------------------------主函数------------------------------------void main(){char choice;while(choice!='q'){ cout<<"\n******************************"<<endl;cout<<" 欢迎使用哈夫曼编码解码系统"<<endl;cout<<"******************************"<<endl;cout<<"(1)要初始化哈夫曼链表请输入'i'"<<endl; cout<<"(2)要编码请输入'e'"<<endl;cout<<"(3)要译码请输入'd'"<<endl;cout<<"(4)要打印编码请输入'p'"<<endl;cout<<"(5)要打印哈夫曼树请输入't'"<<endl;cout<<"(6)要打印译码请输入'y'"<<endl;if(flag==0)cout<<"\n请先初始化哈夫曼链表,输入'i'"<<endl;cin>>choice;switch(choice){case 'i':Initialization();break;case 'e':Encoding();break;case 'd':Decoding();break;case 'p':Code_printing();break;case 't':Tree_printing(HT,2*n-1); break;case 'y':Code_printing1();break;default:cout<<"input error"<<endl; }}free(z);free(w);free(HT);}运行结果：。