#coding:utf-8

class FloatRange:

    def __init__(self,start,end,step=0.1):
        self.start = start
        self.end = end
        self.step = step

    def __iter__(self):
        t = self.start
        while t <=self.end:
            yield t
            t = t + self.step


    def __reversed__(self):
        t = self.end
        while t>= self.start:
            yield t
            t = t-self.step


for x in FloatRange(1.0,3.0,0.2):
    print x

#输出结果如下，缺少3.0这个值，而改成FloatRange(1.0,2.0,0.2)时，就会输出1.0，1.2，1.4，1.6，1.8，2.0

1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8