JRT Pascal  User's Guide     version 3.0         NOT FOR SALE   -154-



      14.   Extended CASE statement

      Format

      CASE selector_expression OF
      label_expression ... , label_expression : statement;
       ...
       ...
      ELSE : statement;
      END


           The  CASE  statement is used to select one of several statements
      for execution based on the value  of  the  selector_expression.   The
      selector_expression and the label_expression must be compatibile data
      types.

           The  label_expressions  are  evaluated  sequentially.  If one is
      found equal to the selector, the corresponding statement is executed.
      If none are  equal,  then  the  optional  ELSE  clause  statement  is
      executed.

           The  ELSE  clause  is  a  JRT  Pascal extension.  Also, standard
      Pascal allows only constants as labels, while expressions are allowed
      by JRT Pascal. Not more than 128 label clauses  are  allowed  in  one
      CASE  statement.   Not  more  than  128  labels  per label clause are
      allowed.  The statements should be  followed  by  a  semicolon.   The
      semicolon is optional on the last statement in the CASE statement.


      Examples:


            CASE I OF
            2 : WRITELN('I IS 2');
            4 : WRITELN('I IS 4');
            ELSE : WRITELN('I IS NOT 2 OR 4');
            END;


            CASE LANGUAGE OF        (* STRING EXPRESSION *)
            'PASCAL'    : YEAR := 1970;
            'PL/I'      : YEAR := 1964;
            'BASIC'     : YEAR := 1965;
            END;














      Compliments of Merle Schnick      SECTION 14:  Extended CASE statement


      JRT Pascal  User's Guide     version 3.0         NOT FOR SALE   -155-



            (* EXAMPLE OF EXPRESSIONS IN LABELS *)
            CASE ANGLE OF
            PHI         : WRITELN('PHI');
            2.0 * PHI   : WRITELN('TWO PHI');
            3.0 * PHI   : WRITELN('THREE PHI');
            ELSE        : WRITELN('ANGLE NOT ON NODE');
            END;


            (* EXAMPLE OF BOOLEAN SELECTOR AND LABEL EXPRESSIONS *)

            (* CHECK VOLTAGE V FOR VALID RANGE *)
            CASE TRUE OF 
            (V > 2.5) AND (V < 4.3)       : PROCESS_RANGE_1;
            (V > 5.6) AND (V <= 14.08)    : PROCESS_RANGE_2;
            (V > 35.6) AND (V <= 100.0)   : PROCESS_RANGE_3;
            ELSE : WRITELN('VOLTAGE OUT OF VALID RANGES:',V);
            END;









































      Compliments of Merle Schnick      SECTION 14:  Extended CASE statement

S_RANGE_3;
            ELSE : WRITELN('VOLTAGE OUT OF VALID RANGES:',V);
            END;