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国外网站上的一些精典的C程序

      C Language Topic:  Clearing a Text Mode DOS PC screen
====================================================================

  Compiled by Mike Demski - [e-mail]

 The following question is often asked in the FidoNet C_ECHO and
 other C/C++ programming forums/areas:

 "How do I clear a "text mode DOS PC" screen using the C Language?"

 Answers to the above question vary.  First, if portability is of
 concern, a portable clear screen function "clrscr()" exists within
 the SNIPPETS archive.  Within SNIPPETS, please refer to:

 "Vidport.C - DOS: Portable gotoxy(), clrscr(), etc. equivalents"

 Also, many compiler vendors supply a clear screen function,
 which is "compiler specific" (i.e. - non portable).  (See below.)

====================================================================
   Compiler (Vendor)     *  Clear Screen Function  *   Header File
====================================================================
 Borland Turbo C++ 3.0,  *        clrscr()         *    conio.h
 Borland C++ 3.x, 4.xx   *                         *
--------------------------------------------------------------------
 M.S. Quick C 2.5,       *                         *
 M.S. Visual C++ 1.52,   *     _clearscreen()      *    graph.h
 Watcom C/C++ 10.x       *                         *
--------------------------------------------------------------------
 Mix Power C 2.2.0       *        clrscrn()        *    bios.h
--------------------------------------------------------------------
 Symantec C++ v7.x,      *  [ See example below ]  *    disp.h
 Zortech C 2.18          *    disp_xxxx() family   *
--------------------------------------------------------------------

Examples of specific vendor approaches to clearing a PC screen in DOS:

--------------------------------------------------------
/* Example - Borland Turbo C++ 3.0, Borland C++ 3.1, and
             Borland C++ 4.x Clear Screen (DOS PC)   */

#include <conio.h>

int main(void)
{
  clrscr();

  return 0;
}
--------------------------------------------------------
--------------------------------------------------------
/* Example - M.S. Quick C 2.5, M.S. VC++ 1.52, and
             Watcom 10.x Clear Screen (DOS PC)   */

#include <graph.h>

int main(void)
{
  _clearscreen(_GCLEARSCREEN);  /* or _clearscreen(0) */

  return 0;
}
--------------------------------------------------------
--------------------------------------------------------
/* Example - Power C 2.2.0 Clear Screen (DOS PC)  */

#include <bios.h>

int main(void)
{
  clrscrn();

  return 0;
}
--------------------------------------------------------

To clear the PC screen in DOS with Symantec C++ or
Zortech C++, use the disp_xxxx() functions to set the
cursor to the beginning of the screen and then call the
disp_eeop() function to erase to the end of the screen.
--------------------------------------------------------
/* Example - Symantec C++ and Zortech C++ (all versions)
             Clear Screen (DOS PC)   */

#include <disp.h>

int main(void)
{
   disp_open();
   disp_move(0, 0);
   disp_eeop();
   disp_close();

   return 0;
}
--------------------------------------------------------
========================================================

Furthermore, when using ANSI.SYS (or an equivalent), one
may clear the screen using ANSI screen control codes.
Within the SNIPPETS archive, please refer to ANSICODE.H,
which defines: ANSI_cls(), or note the following equivalent
ANSI screen control code clear screen example:

--------------------------------------------------------
/* Example - Using ANSI screen control codes to
             Clear Screen (DOS PC)

     Note:   ANSI.SYS or equivalent must be loaded
             for this example to clear the PC screen.  */

#include <stdio.h>

#define  ESC  27

int main(void)
{

  printf("%c[2J", ESC);

  return 0;
}
--------------------------------------------------------