Task

Test whether an integer is even or odd.

There is more than one way to solve this task:

 Use the even and odd predicates, if the language provides them.
 Check the least significant digit. With binary integers, i bitwise-and 1 equals 0 iff i is even, or equals 1 iff i is odd.
 Divide i by 2. The remainder equals 0 iff i is even. The remainder equals +1 or -1 iff i is odd.
 Use modular congruences:
 i ≡ 0 (mod 2) iff i is even.
 i ≡ 1 (mod 2) iff i is odd.


 
BEGIN
 
% RETURN 1 IF EVEN, OTHERWISE 0 %
INTEGER FUNCTION EVEN(I);
INTEGER I;
BEGIN
  EVEN := 1 - (I - 2 * (I / 2));
END;
 
% TEST THE ROUTINE %
INTEGER K;
FOR K := 1 STEP 3 UNTIL 10 DO
  WRITE(K," IS ", IF EVEN(K) = 1 THEN "EVEN" ELSE "ODD");
 
END