源码如下：

def gcd(a,b):

    if b == 0:

        return a

    return gcd(b,a%b)

class Rational(object):

    def __init__(self, p, q):

        self.p = p

        self.q = q

    def __add__(self, r):

        return Rational(self.p * r.q + self.q * r.p, self.q * r.q)

    def __sub__(self, r):

        return Rational(self.p*r.q-self.q*r.p,self.q*r.q)

    def __mul__(self, r):

        return Rational(self.p*r.p,self.q*r.q)

    def __truediv__(self, r):

        return Rational(self.p*r.q,self.q*r.p)

    def __str__(self):

        g = gcd(self.p,self.q)

        return ('%s/%s'%(self.p/g,self.q/g))

    __repr__ = __str__

r1 = Rational(1, 2)

r2 = Rational(1, 4)

print (r1 + r2)

print (r1 - r2)

print (r1 * r2)

print (r1 / r2)

输出结果如下：