Q41159: INFO: rewind(stdin) Clears Keyboard Buffer

Article: Q41159
Product(s): Microsoft C Compiler
Version(s): MS-DOS:5.1,6.0,6.00a,6.00ax,7.0; WINDOWS:1.0,1.5,1.51,1.52; WINDOWS NT:1.0,2.0,2.1,4.0,
Operating System(s): 
Keyword(s): kbcode kbCRT kbVC kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC400 kbVC500 kbVC6
Last Modified: 25-JUL-2001

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The information in this article applies to:

- The C Run-Time (CRT), included with:
   - Microsoft C for MS-DOS, versions 5.1, 6.0, 6.0a, 6.0ax 
   - Microsoft C/C++ for MS-DOS, version 7.0 
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.0, 1.5, 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0, 5.0, 6.0 
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SUMMARY
=======

To clear the keyboard buffer in Microsoft C use the function rewind() with the
stream STDIN, which is associated with the keyboard by default. The function
fflush() clears the buffers that C programs use for stream level I/O. It does
not clear the device buffer.

MORE INFORMATION
================

The following is an example that shows what happens when the keyboard buffer is
not cleared, and then how to clear it:

Sample Code
-----------

  /* Compile options needed: none
  */ 

  #include <stdio.h>

  void main(void)
  {
     int ch ;

     puts( "Input two or more chars. One is read now." );
     ch = getchar();
     putchar( ch );
     putchar( '\n' );

     puts( "The next char is taken from stdin." );
     ch = getchar( );
     putchar( ch );
     putchar( '\n' );

     rewind( stdin );
     puts( "Input two or more chars. One is read now." );
     ch = getchar();
     putchar( ch );
     putchar( '\n' );

     rewind( stdin );
     puts( "You must enter another char because of the rewind(stdin)" );
     ch = getchar( );
     putchar( ch );
     putchar( '\n' );
  }

Additional query words: 8.00 8.00c 9.00 9.10

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Keywords          : kbcode kbCRT kbVC kbVC100 kbVC150 kbVC151 kbVC152 kbVC200 kbVC210 kbVC400 kbVC500 kbVC600 
Technology        : kbVCsearch kbAudDeveloper kbCRT
Version           : MS-DOS:5.1,6.0,6.00a,6.00ax,7.0; WINDOWS:1.0,1.5,1.51,1.52; WINDOWS NT:1.0,2.0,2.1,4.0,5.0
Issue type        : kbinfo

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