Turbo Prolog

If a key has been pressed since the last read operation was performed, inkey succeeds
by binding the variable CharParam to the ASCII character associated with the key
pressed. inkey fails if no key has been pressed. Thus inkey-unlike readchar-allows
execution to continue even if a key has not been pressed. The example below uses
inkey and time to test a person's reaction time.
126
II Program bD II
predicates
wait(char)
equal(char,char)
test(string)
goal
makewindow(3,7,D,IIII,D,D,2S,8D),
makewindow(2,7,7,IIKey to press now ll ,2,S,b,7D),
makewindow(:L,7,7,IIAccepted lettersll ,8,:LD,:LD,bD),
Word = IIPeter Piper picked a peck of pickled peppersll),
write("Please type :\n\tll,Word,\n\t),
time(O,O,O,D),test(Word),
timeL, _, 5, H),
write(lI\nYou took 11,5,11 seconds and II,H,II hundredthsll).
clauses
wait(X):- inkey(Y),equal(X,Y).
wait(X):- shiftwindow(2),write(X),wait(X).
test(W):- frontchar(W,Ch,R),wait(Ch),
shiftwindow(2),write(Ch),test(R).
test(lIlI) .
equal(X,X) :-!.
equal(_,_):-beep,fail.
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