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数据结构教程第十六课串操作应用举例

敬业的IT人 互联网 佚名 2008-1-4 15:28:03

教学目的： 掌握文本编辑的基本原理及方法

教学重点： 简单文本编辑

教学难点： 串的存储管理

授课内容：

一、复习串的堆分配存储表示

堆分配存储表示

二、文本编辑基本原理

图一

文本编辑可以用于源程序的输入和修改（如图一）,也可用于报刊和书籍的编辑排版以及办公室的公文书信的起草和润色（如图二）。

图二

可用于文本编辑的程序很多，功能强弱差别很大，但基本操作是一致的：都包括串的查找，插入和删除等基本操作。

对用户来讲，一个文本（文件）可以包括若干页，每页包括若干行，每行包括若干文字。

对文本编辑程序来讲，可把整个文本看成一个长字符串，称文本串，页是文本串的子串，行又是页的子串。为简化程序复杂程度，可简单地把文本分成若干行。

例：下面的一段源程序可以看成一个文本串，

main(){

float a,b,max;

scanf("%f,%f",&a,&b);

if (a>b) max=a;

else max=b;

};

这个文本串在内存中的存储映像可为：

main(){\nfloata,b,max;\nscanf("%f,%f",&a,&b);\nifa>bmax=a;\nelsemax=b;\n}\n

在编辑时，为指示当前编辑位置，程序中要设立页指针、行指针、字符指针，分别指示当前页，当前行，当前字符。因此程序中要设立页表、行表便于查找。

三、简单行编辑程序例

源程序

#include <conio.h>#include <string.h>#include "keyscode.h"#include "menu.h"struct line{  int charnum;  char *base;};typedef struct line SequListElemType;#include "sequlist.h"#define MAXLINES 1000int key;int cureditline=0;int curscrtopline=0;int cureditcol=0;int funckey;int editwinx=2;int editwiny=3;int editwinlines=20;int mainover=0;FILE *curfile;char filename[255]="test.txt";SequList *Document;char ascii(int k);printdoc(int startfileline,int startscrline);readdoc(FILE *fp);editline(int curline,int maxcolnum){  char s[2000];  setscrcolor(BLUE,YELLOW);  strcpy(s,Document->elem[curline].base);  getstring(editwinx,editwiny curline-curscrtopline,s,maxcolnum);  free(Document->elem[curline].base);  Document->elem[curline].base=(char *)malloc(strlen(s) 1);  strcpy(Document->elem[curline].base,s);}printdoc(int startfileline,int startscrline){  int i;  int j;  cursor_hide();  i=startscrline;  j=startfileline;  setscrcolor(BLUE,YELLOW);  gotoxy(editwinx,editwiny startscrline);  while(i<=editwinlines && i<Document->length)    {      clearscrline(editwinx,editwiny i,78);      putsxy(editwinx,editwiny i  ,Document->elem[j   -1].base);    }  while(i<=editwinlines)    clearscrline(editwinx,editwiny i  ,78);  cursor_show();}getline(FILE *fp,char *l){  int i=0;  while(!feof(fp))    if((l[i  ]=fgetc(fp))=='\n')      break;  l[i-1]='\0';}closedoc(FILE *fp){  int i;  fclose(fp);  for(i=0;i<Document->length;i  )    free(Document->elem[i].base);  SequListDestroy(Document);}readdoc(FILE *fp){  char *newline;  char s[20000];  int linenum=0;  struct line curline;  if(!fp) return;  while(!feof(fp))    {      getline(fp,s);      linenum  ;      newline=(char *)malloc(strlen(s) 1);      strcpy(newline,s);      curline.base=newline;      curline.charnum=strlen(newline);      SequListInsert(Document,linenum,curline);    }}char ascii(int k){  char c;  c=(k<<8)>>8;  if(c>=32&&c<127)    return c;  else    return 0;}insertchar(char *s,char c,int pos){  int i;  for(i=strlen(s) 1;i>pos;i--)    s[i]=s[i-1];  s[i]=c;}deletechar(char *s,int pos){  int i;  int j;  j=strlen(s);  for(i=pos;i<=j;i  )    s[i]=s[i 1];}clearscrline(int x,int y,int num){  int i;  for(i=0;i<num;i  )    putcxy(x i,y,'');}getsindiag(int x,int y,int w,char *title,char *s){  char buf[2000];  gettext(x,y,x w 2,y 2,buf);  setscrcolor(LIGHTGRAY,BLACK);  box(x,y,w 2,3);  putsxy(x 3,y,title);  getstring(x 1,y 1,s,w);  puttext(x,y,x w 2,y 2,buf);}insertnewline(int linenum){  struct line  l;  l.base=(char *)malloc(80);  l.charnum=0;  l.base[0]='\0';  SequListInsert(Document,linenum,l);}deleteline(int linenum){  SequListDelete(Document,linenum);}getstring(int x,int y,char *s,int num){  int k;  int n;  char c;  int curpos=0;  int thisover=0;  cursor_show();/*  putsxy(x,y,s); */  gotoxy(x,y);  while(!thisover)    {      if(k=bioskey(1))       { switch(k){   case KEYEsc:   case KEYReturn:   case KEYUp:   case KEYDown:   case KEYAlt_x:   case KEYCtrl_y:     return;     break;   default:     bioskey(0);   }       }      elsecontinue;      switch(k){case KEYHome:  curpos=0;  gotoxy(x curpos,y);  break;case KEYEnd:  curpos=strlen(s);  gotoxy(x curpos,y);  break;case KEYReturn:  thisover=1;  break;case KEYLeft:  if(curpos) curpos--;  gotoxy(x curpos,y);  break;case KEYRight:  if(curpos<num) curpos  ;  gotoxy(x curpos,y);  break;case KEYDelete:  if(curpos<strlen(s))   {     deletechar(s,curpos);     cursor_hide();     clearscrline(x,y,num);     putsxy(x,y,s);     gotoxy(x curpos,y);     cursor_show();   }  break;case KEYBackspace:  if(curpos)    {      deletechar(s,curpos-1);      curpos--;              cursor_hide();      clearscrline(x,y,num);      putsxy(x,y,s);      gotoxy(x curpos,y);      cursor_show();    }  break;case KEYEsc:  return;default:  c=ascii(k);  if (c&&strlen(s)<num)    {      insertchar(s,c,curpos);      cursor_hide();      clearscrline(x,y,num);      curpos  ;      putsxy(x,y,s);      gotoxy(x curpos,y);      cursor_show();    }break;      }    }}dofunc(int itemno){   switch(itemno)    {      case 0: break;      case 1:  /*Open file*/ getsindiag(3,4,50,"Open file Name",filename); if(curfile=fopen(filename,"r "))   {     readdoc(curfile);     printdoc(1,0);   } break;      case 3:mainover=1;break;      case 21:showmessagew();      default:break;    }}main(){ int i;  char c;  char  *mainmenuitem[10]={"File","Edit    ","Help"};  char  *submenu1[10]={"New","Open","Save","Exit to system"};  char  *submenu2[10]={"Copy","Cut","Paste   "};  char  *submenu3[20]={"HelpContent","About"};  initmenu(MAINMENU_V,3,&mainmenu,mainmenuitem);  initmenu(SUBMENU_H,4,&submenu[0],submenu1);  initmenu(SUBMENU_H,3,&submenu[1],submenu2);  initmenu(SUBMENU_H,2,&submenu[2],submenu3);  for(i=0;i<3;i  )    addsubmenu(&mainmenu,i,&submenu[i]);  definemenupos(3,1,&mainmenu);  cursor_hide();  showmenu(&mainmenu);  showmainw(1,2,80,23);  showmessagew();  SequListInit(&Document,MAXLINES);  insertnewline(1);  setscrcolor(BLUE,YELLOW);  while(!mainover)  {    if(key=bioskey(1))      {if(!ascii(key))bioskey(0);      }    else      continue;    switch(key){case KEYBackspace:case KEYDelete:case KEYHome:case KEYEnd:case KEYReturn:  if(cureditline-curscrtopline<editwinlines)    cureditline  ;  else    {       curscrtopline  ;       printdoc(curscrtopline 1,editwiny);    }  insertnewline(cureditline 1);  printdoc(curscrtopline 1,0);  gotoxy(editwinx,editwiny cureditline);  editline(cureditline,78);  break;case KEYUp:  if (cureditline>0)    {      cureditline--;      gotoxy(editwinx,editwiny cureditline);      editline(cureditline,78);    }  break;case KEYDown:  if (cureditline<Document->length-1)    {      cureditline  ;      gotoxy(editwinx,editwiny cureditline);      editline(cureditline,78);    }  break;case KEYCtrl_y:  deleteline(cureditline 1);  if(Document->length==0)    insertnewline(cureditline 1);  if(cureditline>=Document->length)    insertnewline(cureditline 1);  printdoc(cureditline 1,cureditline-curscrtopline);  gotoxy(editwinx,editwiny cureditline);  editline(cureditline,78);  break;case KEYLeft:case KEYRight:          break;case KEYCtrl_s:  break;case ESC:   cursor_hide();   dofunc(getmenuitem());   break;case KEYAlt_x:  mainover=1;  break;default:  gotoxy(editwinx,editwiny cureditline-curscrtopline);  editline(cureditline,78);  break;    }  }  closedoc(curfile);  setscrcolor(BLACK,WHITE);  clrscr();  cursor_show();}

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