1现在参照上面的编码伪代码可以试着用所学的C语言来实.doc

1现在参照上面的编码伪代码可以试着用所学的C语言来实现它：void compress(FILE *in,FILE *out,struct cell *dic)FILE *ifp,*ofp;struct cell *table;char c2,*ctemp,*p;int j; ifp=in;ofp=out;table=dic; ctemp=malloc(sizeof(char);p=malloc(sizeof(char); p0=0;c0=fgetc(ifp);c1=0; while(!feof(ifp)/*逐步单个字符读ifp文本文件知道文件结束*/ strcpy(ctemp,p);strcat(ctemp,c); if(j=inthetable(ctemp,table)!=-1)/*函数inthetable(ctemp,table)是判断字符串ctemp是否在字典table中，它的返回值是ctem在字典table中的位置，但若ctemp不存在则返回-1.*/strcpy(p,ctemp); else j=inthetable(p,table);fwrite(&j,sizeof(int),1,ofp);/*把整数j写入ofp文件中，ofp实指向被压缩文件的指针*/addtodictionary(ctemp,table);/*函数addtodictionary(ctemp,table)是把字符串ctemp加入到字 table的尾部*/strcpy(p,c); c0=fgetc(ifp); j=inthetable(p,table); fwrite(&j,sizeof(int),1,ofp);/*End the Compress()*/对于子函数inthetable()和addtodictionary我们可以暂时只要明确它们的功能，具体实现可以留在后面再做2现也用C语言来实现它：void expand(FILE *in,FILE *out,struct cell *dic)FILE *ifp,*ofp;struct cell *table,*dtemp,*dtemp1; int cw,pw,i,j,length,*w; char *ctemp,*p,c2; w=malloc(sizeof(int);ctemp=malloc(sizeof(char);p=malloc(sizeof(char); ifp=in;ofp=out;table=dic; dtemp=table; for(i=1;inext; dtemp1=dtemp-next; dtem是判断字典的位置cw，后者是判断字符串ctemp*/ temp1=table; for(i=1;inext; strcpy(ctemp,dtemp1-point);length=strlen(ctemp); fwrite(ctemp,sizeof(char),length,ofp); dtemp1=table; for(i=1;inext; strcpy(p,dtemp1-point); dtemp1=table; for(i=1;inext; c0=*(dtemp1-point);c1=0; strcpy(ctemp,p); strcat(ctemp,c);addtodictionary(ctemp,table);else dtemp1=table; for(i=1;inext; strcpy(p,dtemp1-point);dtemp1=table; for(i=1;inext; c0=*(dtemp1-point);c1=0; strcpy(ctemp,p); strcat(ctemp,c); length=strlen(ctemp); fwrite(ctemp,sizeof(char),length,ofp); addtodictionary(ctemp,table); /*End The Expand()*/现在我们所剩下的只有inthetable(),addtodictionary()和inthestringtable()三个子函数的实现问题了，按照自己事先所预定的函数功能，可以很容易给出这三个字函数的C语言描述：int inthetable(char *c,struct cell *dic)char *ctemp;struct cell *table;int j=0; ctemp=malloc(sizeof(char);strcpy(ctemp,c);table=dic; while(table!=NULL) if(strcmp(table-point,ctemp)=0) return(j);/*存在*/ elsetable=table-next；j+; return(-1);/*不存在*/* End the inthetable()*/void addtodictionary(char *p,struct cell *dic)char *ctemp;struct cell *table,*dtemp;int i;ctemp=malloc(sizeof(char); strcpy(ctemp,p);table=dic; for(i=1;inext; dtemp=(struct cell *)malloc(sizeof(struct cell); strcpy(dtemp-point,ctemp); table-next=dtemp;dtemp-next=NULL;n+;/*n为全局变量，用来纪录字典的长度*/*End the addtodictionary()*/int inthestringtable(int k,struct cell *dic) struct cell *dtemp;int j=0;dtemp=dic; while(dtemp-next!=NULL) if(jnext;j+; else if(j=k)return(j);/*存在*/if(j=k) return(j); else return(-1);/*不存在*/四、程序的进一步实现（源代码）：#include#includestruct cellchar point100;struct cell *next;*dictionary;void compress();void expand();void addtodictionary();void *malloc();int inthetable();int inthestringtable();int n=31;main() int choise,i; char *infilename,*outfilename;FILE *infile,*outfile; struct cell *dtemp1,*dtemp2; infilename=malloc(sizeof(char);outfilename=malloc(sizeof(char); dictionary=(struct cell *)malloc(sizeof(struct cell); *(dictionary-point)=44;*(dictionary-point)+1)=0; dtemp1=(struct cell*)malloc(sizeof(struct cell); dictionary-next=dtemp1;*(dtemp1-point)=46;*(dtemp1-point)+1)=0; dtemp2=(struct cell*)malloc(sizeof(struct cell); dtemp1-next=dtemp2;*(dtemp2-point)=58;*(dtemp2-point)+1)=0;dtemp1=dtemp2; dtemp2=(struct cell*)malloc(sizeof(struct cell); dtemp1-next=dtemp2;*(dtemp2-point)=59;*(dtemp2-point)+1)=0;dtemp1=dtemp2; dtemp2=(struct cell*)malloc(sizeof(struct cell); dtemp1-next=dtemp2;*(dtemp2-point)=10;*(dtemp2-point)+1)=0;dtemp1=dtemp2; dtemp2=(struct cell*)malloc(sizeof(struct cell); dtemp1-next=dtemp2;*(dtemp2-point)=13;*(dtemp2-point)+1)=0;dtemp1=dtemp2; for(i=97;inext=dtemp2;dtemp2-next=NULL; dtemp1=dtemp2; *(dtemp2-point)=i;*(dtemp2-point)+1)=0; /*Dui Ditionary Chu SHi Hua*/ printf(n for Compress.n for Expand.n for Exit!n ); printf(Please Input Your Choise:); scanf(%d,&choise); if(choise=1) printf(nPlease Input The Compressing File Name:); scanf(%s,infilename); if(infile=fopen(infilename,rb)=NULL) printf(Cannot open the %s file!n,infilename);exit(1); printf(nPlease Input The Name for the Compressed File:); scanf(%s,outfilename); if(outfile=fopen(outfilename,wb)=NULL) printf(Cannot open the %s file!n,outfilename);exit(1); compress(infile,outfile,dictionary);/*Can Compress*/ fclose(infile); fclose(outfile); else if(choise=2) printf(nPlease Input THe Expanding File Name:); scanf(%s,infilename); if(infile=fopen(infilename,rb)=NULL) printf(Cannot open the %s file!n,infilename);exit(1); printf(nPlease INput the Name for THe Expanded File:); scanf(%s,outfilename); if(outfile=fopen(outfilename,wb)=NULL) printf(Cannot open the %s file!n,outfilename);exit(1); /*if(infile=fopen(infilename,rb)=NULL|(outfile=fopen(outfilename,wb)=NULL)printf(Cannot Open THe %s File or The %s File!n,infilename,outfilename);exit(1); else*/ expand(infile,outfile,dictionary);/*Can Expand*/ fclose(infile);fclose(outfile); else exit(1);void compress(FILE *in,FILE *out,struct cell *dic) FILE *ifp,*ofp;struct cell *table;char c2,*ctemp,*p;int j; ifp=in;ofp=out;table=dic; ctemp=malloc(sizeof(char);p=malloc(sizeof(char); p0=0;c0=fgetc(ifp);c1=0; while(!feof(ifp) strcpy(ctemp,p);strcat(ctemp,c); if(j=inthetable(ctemp,table)!=-1)strcpy(p,ctemp); else j=inthetable(p,table);printf( %d.,j);fwrite(&j,sizeof(int),1,ofp);addtodictionary(ctemp,table);strcpy(p,c); c0=fgetc(ifp); j=inthetable(p,table); printf( %d.,j); fwrite(&j,sizeof(int),1,ofp);/*End the Compress()*/int inthetable(char *c,struct cell *dic) char *ctemp;struct cell *table;int j=0; ctemp=malloc(sizeof(char); strcpy(ctemp,c);table=dic;while(table!=NULL) if(strcmp(table-point,ctemp)=0) return(j); else table=table-next; j+; return(-1);/* End the inthetable()*/void addtodictionary(char *p,struct cell *dic) char *ctemp;struct cell *table,*dtemp;int i; ctemp=malloc(sizeof(char); strcpy(ctemp,p);table=dic; for(i=1;inext; dtemp=(struct cell *)malloc(sizeof(struct cell); strcpy(dtemp-point,ctemp); table-next=dtemp;dtemp-next=NULL; n+;/*End the addtodictionary()*/void expand(FILE *in,FILE *out,struct cell *dic) FILE *ifp,*ofp;struct cell *table,*dtemp,*dtemp1; int cw,pw,i,j,length,*w; char *ctemp,*p,c2; w=malloc(sizeof(int);ctemp=malloc(sizeof(char);p=malloc(sizeof(char); ifp=in;ofp=out;table=dic; /*Chong Xin Ding Yi n*/ dtemp=table; for(i=1;inext; dtemp1=dtemp-next; dtemp-next=NULL; for(i=33;inext; free(dtemp1); dtemp1=dtemp; /*Chong Xin Ding YIi Dictionary*/ j=fread(w,sizeof(int),1,ifp); cw=*w;printf( %d.,cw); dtemp=table; for(i=1;inext; strcpy(ctemp,dtemp-point);length=strlen(ctemp); while(j!=0) pw=cw; j=fread(w,sizeof(int),1,ifp); cw=*w;printf( %d.,cw); if(i=inthestringtable(cw,dic)!=-1) dtemp1=table; for(i=1;inext; strcpy(ctemp,dtemp1-point); length=strlen(ctemp); fwrite(ctemp,sizeof(char),length,ofp); dtemp1=table; for(i=1;inext; strcpy(p,dtemp1-point); dtemp1=table; for(i=1;inext; c0=*(dtemp1-point);c1=0; strcpy(ctemp,p); strcat(ctemp,c); addtodictionary(ctemp,table); else dtemp1=table; for(i=1;inext; strcpy(p,dtemp1-point); dtemp1=table; for(i=1;inext; c0=*(dtemp1-point);c1=0; strcpy(ctemp,p); strcat(ctemp,c); length=strlen(ctemp); fwrite(ctemp,sizeof(char),length,ofp); addtodictionary(ctemp,table); /*End The Expand()*/int inthestringtable(int k,struct cell *dic) struct cell *dtemp;int j=0; dtemp=dic; while(dtemp-next!=NULL) if(jnext; j+; else if(j=k)return(j); if(j=k) return(j); else return(-1);五、程序的调试：通过调试，在排除程序的所有语法，算法错误和所有的警告后，对程序进行初步尝试性运行，我先新建一文本文件c:tczk.txt，其内容只由小写字母“a,b,c,“和“，。；：“以及回车和换行符组成的“abacaba”,然后运行LZW.C: for Compress. for Expand. for Exit! Please Input Your Choise:1Please Input The Compressing File Name:d:tcas.txtPlease Input The Name for the Compressed File:d:tc123.txt元文本文件zk.txt的文件大小是7字节，被压缩后的文件123.txt文件大小却是12字节，显然没有起到我们前面所预期的压缩功能，仔细思索其中的缘故，发现问题的所在是我们对这两个文件所进行的操作方式的差异- 我们对zk.txt文件的读入方式用的是fgetc(ifp)，也就是说是按照字符大小为单位的，而我们在对123.txt文件的写入操作用得却是fwrite(&j,sizeof(int),1,ofp);址操作是按照整数大小为单位来进