setbuf() Doesn't Control MS-DOS Buffer or Keyboard Buffer (45563)

MORE INFORMATION

The function setbuf() affects a stream file buffer, such as stdin, but has no effect on the keyboard or MS-DOS device buffers. The stream I/O function getchar() can read a character from the keyboard buffer only when the keyboard buffer is flushed by either being filled, by a carriage return, or by an interrupt 0x21, function 0xC call.

To read normal characters directly from the keyboard, you can use the console I/O function getch(). To read control codes such as ALT+Q (echo subsequent output to printer) or ALT+R (pause output), you can use the _bios_keybrd() function. For more information on this function, query on the following word in the Microsoft Knowledge Base:

   _bios_keybrd()
				

The following example demonstrates the difference between using getchar() and getch().

Sample Code

/* Compile options needed: none
*/ 

#include <stdio.h>
#include <conio.h>

void main (void)

{
   setbuf (stdin, NULL);        /* cause stdin to be unbuffered */ 
   if (getchar () != EOF )
      printf ("getchar() still waits for return key\n");
   if (getch () != EOF )
      printf ("getch() does not wait for return key\n");
}