tchkf.doc

c语言函数库,包括大部分c语言函数的说明和代码,有利于想深入了解c编程的开发人员.

  Prototype in        doshk.h
  
  Remarks             remove a CED installable command. The command
                      parameter should be terminated by a CR.
  
  Return value        returns TRUE if successful, FALSE otherwise. If
                      unsuccessful, _doserrno will contain the error
                      code:
  
                           0x01      invalid function
                           0x02      command not found
  
                      If CED is not installed, _doserrno & 0xFF00 will
                      return 0xFF00.
  
  See also            CEDadd(), isCEDavail()
  










































     TCHK 2.1                                                    Page 26

  
  Function             center - coordinate to center a message on screen
  
  Syntax              int center(char *str);
  
  Prototype in        video.h
  
  Remarks             center() will determine the proper X-coordinate to
                      display str centered horizontally with the current
                      window area. See Borland's explanation of window()
                      and related topics for further details.
  
  Return value        returns X coordinate to display str centered
                      horizontally within the window() corrdinates.
  
  Example             #include <video.h>
  
                      main()
                      {
                           char msg[] = "This will be centered on line 3"
  
                           gotoxy(center(msg),3);
                           cputs(msg);
                      }
  
  Program output      
  
                                          This will be centered on line 3
  
  


































     TCHK 2.1                                                    Page 27

  
  Function             changelitebar - set internal litebar menu 
                                           information
  
  Syntax              void changelitebar(struct litebar_header *lh,
                                         struct litebar_field *lf)
  
  Prototype in        menuhk.h
  
  Remarks             sets internal variables for a litebar menu
                      regarding the currently hilited item.
  
                      This function is used internally by several
                      litebar...() menu functions.
  
  Return value        nothing.
  
  Note                This function is for internal uses only.
  
  See also            menuhk.h
                      isHiliteable(), litebar_alloc(), litebar_free(),
                      litebar_get(), litehilite(), litemessage(),
                      liteunhilite(), menu_litebar()
                      litebarerrno
  
  






































     TCHK 2.1                                                    Page 28

  
  Function             Checksum_block - calculate checksum for a block
  
  Syntax              unsigned char Checksum_block(char *b, int size);
  
  Prototype in        comm.h
  
  Remarks             calculates a checksum value based on the block
                      given. A checksum value is commonly used by older
                      transmission protocols such as Xmodem.
  
  Return value        returns a checksum value for the block operated on.
  
  See also            CRC16_block(), CRC16tupdate(), CRC16update(),
                      CRC32tupdate()
  
  















































     TCHK 2.1                                                    Page 29

  
  Function             clear - clears a portion of the screen
  
  Syntax              void clear(int left, int top, int right,
                                 int bottom);
  
  Prototype in        video.h
  
  Remarks             clears a box of the screen via gotohv() and putk().
                      All screen coordinates are absolute.
  
  Return value        nothing.
  
  See also            cls(), gotohv(), putk()
  
  Example             #include <video.h>
  
                      main()
                      {
                           clear(0,0,79,3);    /* clear top 4 lines */
                      }
  










































     TCHK 2.1                                                    Page 30

  
  Function             clear_typeahead - clear typeahead buffer
  
  Syntax              int clear_typeahead(void);
  
  Prototype in        keyboard.h
  
  Remarks             clears the typeahead buffer and returns the number
                      of keystrokes cleared
  
  Return value        number of keystrokes emptied from the typeahead
                      buffer
  
  Example             #include <keyboard.h>
                      #include <stdio.h>
  
                      main()
                      {
                           printf("# keystrokes emptied = %d",
                                  clear_typeahead());
                      }
  










































     TCHK 2.1                                                    Page 31

  
  Function             cls - clear screen
  
  Syntax              #include <video.h>
                      cls();
  
  Prototype in        video.h
  
  Remarks             clears screen by Borland's clrscr(). I hated their
                      name for it, so I #defined cls().
  
  Return value        nothing.
  
  See also            clear()
  
  Example             #include <video.h>
  
                      main()
                      {
                           cls()
                      }
  
  









































     TCHK 2.1                                                    Page 32

  
  Function             color - make a single attribute
  
  Syntax              #include <video.h>
                      color(f,b)
  
  Prototype in        video.h
  
  Remarks             converts a color for a foreground and background
                      attribute in foreground format (0-15) to a single
                      byte.
  
                      This function is a macro.
  
  Return value        returns an attribute byte of foreground ORed with
                      the background shifted left 4 bits.
  
  














































     TCHK 2.1                                                    Page 33

  
  Function             commit - flush disk buffers for to a handle
  
  Syntax              boolean commit(int handle);
  
  Prototype in        doshk.h
  
  Remarks             commit will flush all disk buffers associated with
                      a handle. If DOS 3.3 or later is active, DOS