Microsoft KB Archive/36397

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

Article ID: 36397

Article Last Modified on 8/16/2005



APPLIES TO

  • Microsoft QuickBasic 4.0
  • Microsoft QuickBASIC 4.0b
  • Microsoft BASIC Compiler 6.0
  • Microsoft BASIC Compiler 6.0b
  • Microsoft BASIC Professional Development System 7.0



This article was previously published under Q36397

SUMMARY

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.

MORE INFORMATION

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$


Additional query words: QuickBas BasicCom

Keywords: KB36397