{BEGIN:  EUCLID.TXT         4 18-Dec-85     6   512  Textfile }
PROGRAM Euclid;

  {This programs uses Euclid's method to determine the greatest common
   divisor of two integers.

   efg, 26 January 1985.  See p. 12 of "Algorithms" by Robert Sedgewick.

   Sample Data:
     Input:  1128 1272     Output:  24  }

  VAR
    x,y:  INTEGER;


  FUNCTION gcd(u,v:  INTEGER):  INTEGER;
    VAR
      t:  INTEGER;
  BEGIN
    WHILE v <> 0
    DO BEGIN
      t := u MOD v;
      u := v;
      v := t
    END;
    gcd := u       // Use RESULT := u in Delphi (efg, Oct 2000)
  END {gcd};

BEGIN
  REPEAT
    WRITELN ('Enter two numbers (0s to quit):  ');
    READLN (x,y);
    IF   (ABS(x) > 0) AND (ABS(y) > 0)
    THEN WRITELN ('Greatest common divisor for ',x,' and ',y,' is ',gcd(x,y))
  UNTIL (x = 0) OR (y = 0)
END {Euclid}.

{END:  CS217:EUCLID.TEXT  }