The CLEARINPUT statement clears the type-ahead buffer to allow the next INPUT statement to force a response from the user.
CLEARINPUT only clears the type-ahead buffer. It does not clear data stacked with the DATA statement.
The CLEARINPUT statement is synonymous with INPUTCLEAR.
In the following example, the CLEARINPUT statement clears the terminal type-ahead buffer to provoke a response from the user to the prompt:
PRINT "DO YOU WANT TO DELETE THIS FILE?(Y OR N)"; INPUT X,1