ELSEIF ☆☆

(1) An IF ~ END IF block can contain an ELSEIF line.


IF logical_exp1 THEN
  ………1
ELSEIF logical_exp2 THEN 
  ………2
ELSE 
  ………3
END IF


is equivalent to

IF logical_exp1 THEN
  ………1
ELSE
  IF logical_exp2 THEN
    ………2
  ELSE 
    ………3
  END IF
END IF



If logical_exp1 is true, ………1 shall be executed, otherwise logical_exp2 is true, ………2 shall be executed, otherwise ………3 shall be executed.

Example.

  ! Solve a quadratic equation
  INPUT a, b, c
  LET D=b^2-4*a*c
  IF D>0 THEN
     PRINT (-b+sqr(D))/(2*a),(-b-sqr(D))/(2*a)
  ELSEIF D=0 THEN
     PRINT -b/(2*a)
  ELSE
     PRINT "no solution"
  END IF
  END



(2) An IF~END IF block can contain more than one ELSEIF line.

IF logical_exp1 THEN
………1
ELSEIF logical_exp2 THEN
………2
ELSEIF logical_exp3 THEN
………3
~~~
~~~
ELSEIF logical_expn-1 THEN
………n-1
ELSE
………n
END IF