因为sum(a for a in args)得到的是一个整形，len(args)也是整形，所以b自然也只能是整形

代码供你参考：

def average(*args):

    b=0.00

    if len(args)!=0:

        b=sum(a for a in args) *1.0/ len(args)

        return b

    elif len(args)==0:

        return 0.0

print average()

print average(1, 2)

print average(1, 2, 2, 3, 4)

def average(*args):

      b=0.00

      if len(args)!=0:

          print len(args)

          print sum(a for a in args)

          b=sum(a for a in args) *1.0/ len(args)

          return b

      return 0

print average()

print average(1, 2)

print average(1, 2, 2, 3, 4)