执行代码的时候，输出的结果中含有一个“None”
from python1.python10.car import Car
class Battery():
"""A simple attempt to model a battery for an electric car."""
def __init__(self, battery_size=60):
"""Initialize the batteery's attributes."""
self.battery_size = battery_size
def describe_battery(self):
"""Print a statement describing the battery size."""
print("This car has a " + str(self.battery_size) + "-kWh battery.")
def get_range(self):
"""Print a statement about the range this battery provides."""
if self.battery_size == 60:
range = 140
elif self.battery_size == 85:
range = 185
message = "This car can go approximately " + str(range)
message += " miles on a full charge."
print(message)
print(range)
class ElectricCar(Car):
"""Models aspects of a car, specific to electric vehicles."""
def __init__(self, manufacturer, model, year):
"""
Initialize attributes of the parent class.
Then initialize attributes specific to an electric car.
"""
super().__init__(manufacturer, model, year)
self.battery = Battery()
my_tesla=ElectricCar('tesla','model s',2016)
print(my_tesla.get_descriptive_name())
my_range=Battery()
print（my_range.get_range()）
结果如下
2016 Tesla Model S
2016 Tesla Model S
This car can go approximately 140 miles on a full charge.
140
None
只要将最后一行代码的print() 去掉即可 改成 my_range.get_range() 或者是将 函数中的print(range) 改成 return range
是因为python函数使用return返回值，如果不用
return, 而用print输出值，这个函数默认还有一个返回值为None