Q36397: Must Use A$=INKEY$ after SLEEP to Clear Keyboard Buffer

Article: Q36397
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom | mspl13_basic
Last Modified: 15-DEC-1989

The SLEEP statement was introduced in QuickBASIC Version 4.00b and
in Microsoft BASIC Compiler Version 6.00 for MS-DOS and MS OS/2.
SLEEP does not clear the buffer when a key is pressed. Therefore, the
next input statement will read the pressed keys to clear prior SLEEP
commands.

This information applies to Microsoft QuickBASIC Versions 4.00b and
4.50 for MS-DOS, to Microsoft BASIC Compiler Versions 6.00 and 6.00b
for MS-DOS and MS OS/2, and to Microsoft BASIC PDS Version 7.00 for
MS-DOS and MS OS/2.

The following code example demonstrates the problem with a workaround:

CLS
FOR i = 1 TO 5
  PRINT "press a key please"
  SLEEP
' If you want to clear the buffer, insert the following statement:
'   x$ = INKEY$
NEXT
CLS
'  If you do not clear the buffer, this INPUT prompts with a print
'  of the 5 characters pressed in the FOR loop above, and the value of
'  a$ will be those 5 characters plus any entered at the prompt.
INPUT a$
PRINT a$

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