(Prolog) Switch statement

Using the cut, !, you can make statements similar to a switch statement in other programming languages (e.g. C++).

% If the user enters a number from 1 to an including 3
% the right clauses are called.
% If you would remove the cuts,
% then the input '2' would results in calling both action(2) and action(_)
%
% Note that you can remove 'nondeterm' from the action's predicate,
% but I left it in, so you do can comment out the cuts
PREDICATES
	nondeterm action(integer)
	
CLAUSES
	action(1) :- 
	!,
	nl,
	write("You typed one").
	
	action(2) :- 
	!,
	nl,
	write("You typed two").
	action(3) :- 
	!,
	nl,
	write("You typed three").
	action(_) :- 
	!,
	nl,
	write("You typed an unknown number").
	
GOAL
	write("Type a number from 1 to 3: "),
	readInt(Num),
	action(Num),
	nl.

See also Prolog and C++ syntax comparison.

'switch' links

last edited (February 7, 2007) by bilderbikkel, Number of views: 1026, Current Rev: 3 (Diff)

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