database
	barchart(integer)
	chartbar(integer,integer,integer,integer,integer,integer)
 
global predicates
 bar(integer,integer,integer,integer,integer)-(i,i,i,i,i) language c
predicates
	process(char)
	repeat	
	retractall
	drawbar(integer,integer,integer,integer)
	
goal
	graphics(1,0,0),
	asserta(barchart(0)),
	makewindow(1,1,1,"Bar",0,0,20,40),
	makewindow(2,1,1,"",20,0,4,40),
	repeat,
	write("Press any key to continue"), readchar(_),
	clearwindow,
	makewindow(1,1,1,"Bar",0,0,20,40),
	write("m. Make a bar Chart.\n"),
	write("s. Save your bar Chart.\n"),
	write("l. Load your bar Chart.\n"),
	write("d. Draw your bar Chart.\n"),
	write("e. End\nEnter Choice: "),
	readchar(Choice),
	clearwindow,
	shiftwindow(2),
	process(Choice),
	bios(16,reg(3,0,0,0,0,0,0,0),_).	
	
clauses
	 process('m'):-
			barchart(Nu),
			retract(barchart(Nu)),
			NewNu = Nu+1,
			asserta(barchart(NewNu)),
			write("Enter the number of bars: "),
			readint(NuOfBars),clearwindow,
			write("Enter max value on Y scale: "),
			readint(Max),clearwindow,
			YScale = 140/Max,
			Width = 265/NuOfBars,
			Start = 305-Width,
			clearwindow,
			drawbar(NuOfBars, Width, Start, Yscale),			
			fail.
	 process('s'):-
			write("Enter file name of chart: "),readln(Name),
			concat(Name,".CHT",FName),save(Fname),fail.
	 process('l'):-
			retractall,
			write("Enter file name of chart: "),readln(Name),
			concat(Name,".CHT",FName),consult(FName),fail.
	 process('d'):-
			 barchart(Chart), 
			 chartbar(Chart,XPosition,Ypos,Width,YBarSize,1),
			 bar(XPosition,Ypos,Width,YBarSize,1),fail.
	 process('e').
			
	 drawbar(0,_,_,_):-!.
	 drawbar(Nu,Width,XPosition,Yscale):-
			XNuNew=Nu-1,clearwindow,
			write("Enter the value associated bar ",Nu ,": "),
			readint(Y),
			YBarSize=Y*YScale,
			Ypos=140 - YBarSize,
			bar(XPosition,Ypos,Width,YBarSize,1),
			barchart(Chart),
			asserta(chartbar(Chart,XPosition,Ypos,Width,YBarSize,1)),
			XNewPos= XPosition-Width-5,
			drawbar(XNuNew,Width,XNewPos,Yscale).

repeat.
repeat:- repeat.  
retractall:- retract(_),fail.
retractall.