PROGRAM 15


PROGRAM GREATESTCOMMONDENOMINATOR;
        {ANTHONY F. ORTIZ, ASSIGNMENT 5, JUNE 29. 1994}
        {THIS PROGRAM FINDS THE GCD AND PRINTS IT TO THE SCREEN.}

USES CRT;

VAR
   A, B, A2, B2, GCD:  INTEGER;
                 ANS:  STRING;

PROCEDURE INPUTINTEGERS;

BEGIN
     WRITE ('ENTER FIRST POSITIVE INTEGER.  ');
     READLN (A);
     WRITE ('ENTER SECOND POSITIVE INTEGER. ');
     READLN (B);
     WRITELN;
END;

PROCEDURE FINDGCD;

BEGIN
     A := (ABS (A));
     B := (ABS (B));
     A2 := A;
     B2 := B;
     IF A * B = 0 THEN
        WRITELN (A, ' AND ', B, ' DON''T HAVE A GREATEST COMMON DENOMINATOR. ')
     ELSE
        IF A = B THEN
           ELSE
              REPEAT
                    IF A > B THEN
                       A := A - B
                    ELSE
                       B := B - A;
              UNTIL A = B;
     IF (A = B) AND (A * B <> 0) THEN
        WRITELN (B, ' IS THE GREATEST COMMON DENOMINATOR OF ', A2, ' AND ', B2, '.');
END;

PROCEDURE INQUIRY;

BEGIN
     WRITELN;
     WRITE ('WOULD YOU LIKE TO CONTINUE INPUTTING INTEGERS?  TYPE "NO" TO QUIT. ');
     READLN (ANS);
END;

BEGIN
     REPEAT
           CLRSCR;
           INPUTINTEGERS;
           FINDGCD;
           INQUIRY;
     UNTIL (ANS = 'NO') OR (ANS = 'no');
END.

{  OUTFILE:  PROG15.OUT  }

ENTER FIRST POSITIVE INTEGER.  2
ENTER SECOND POSITIVE INTEGER. 4

2 IS THE GREATEST COMMON DENOMINATOR OF 2 AND 4.

WOULD YOU LIKE TO CONTINUE INPUTTING INTEGERS?  TYPE "NO" TO QUIT. no




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