1.创建和使用类
###1.创建dog()类
class Dog():#定义一个名为dog()的类，类的首字母得大写
#一次模拟小狗的简单尝试
def __init__(self, name, age):#类中的函数称为方法,定义了self, name, age三个形参，必须在方法定义中包含形参self,因为python调用 _init__（）方法创建Dog()类时，将自动传入实参self
#每个与类相关联方法调用都自动传递实参self,它是一个指向实例本身的引用，让示例能够访问类中的属性和方法
#初始化属性name和age
#只需给后两个形参提供值
self.name = name
self.age = age
def sit(self):
#模拟小狗被命令时蹲下
print(self.name + 'is now sitting')
def roll_over(self):
#模拟小狗被命令时打滚
print(self.name + 'is now rolled over')
===========================================
###2.根据类创建实例
class Dog():#定义一个名为dog()的类，类的首字母得大写
#一次模拟小狗的简单尝试
def __init__(self, name, age):#类中的函数称为方法,定义了self, name, age三个形参，必须在方法定义中包含形参self,因为python调用 _init__（）方法创建Dog()类时，将自动传入实参self
#每个与类相关联方法调用都自动传递实参self,它是一个指向实例本身的引用，让示例能够访问类中的属性和方法
#初始化属性name和age
#只需给后两个形参提供值
self.name = name
self.age = age
def sit(self):
#模拟小狗被命令时蹲下
print(self.name + 'is now sitting')
def roll_over(self):
#模拟小狗被命令时打滚
print(self.name + 'is now rolled over')
my_dog = Dog('da ming', 3)
#访问属性
print('my dog name is ' + my_dog.name)
print('my dog is ' + str(my_dog.age) + 'years old')
my dog name is da ming
my dog is 3years old
#调用方法
my_dog.sit()
my_dog.roll_over()
da mingis now sitting
da mingis now rolled over
#创建多个实例
class Dog():
#一次模拟小狗的简单尝试
def __init__(self, name, age)
self.name = name
self.age = age
def sit(self):
print(self.name + 'is now sitting')
def roll_over(self):
print(self.name + 'is now rolled over')
my_dog = Dog('da ming', 3)
your_dog = Dog('ni ni', 3)
print('my dog name is ' + my_dog.name)
print('my dog is ' + str(my_dog.age) + 'years old')
my_dog.sit()
print('\nyour dog name is ' + your_dog.name)
print('your dog is ' + str(your_dog.age) + 'years old')
your_dog.sit()
my dog name is da ming
my dog is 3years old
da mingis now sitting
your dog name is ni ni
your dog is 3years old
ni niis now sitting
2.使用类和实例
#1.编写一个表示汽车的类
class Car():
#一次模拟汽车的简单尝试
def __init__(self, make, model, year):#初始化描述汽车的属性
self.make = make
self.model = model
self.year = year
def get_descriptive_name(self):
#返回整洁的描述信息
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
2016 audi a4
==========================================
#2.给属性指定默认值
class Car():
def __init__(self, make, model, year):
#初始化描述汽车的属性
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0 #添加一个名为odometer_reading的属性，初始值为0
def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name
def read_odometer(self):
#打印一条指出汽车里程的消息
print('this car has ' + str(self.odometer_reading) + ' miles on it')
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.read_odometer()
2016 audi a4
this car has 0 miles on it
===================================================
#修改属性的值
#直接修改
class Car():
def __init__(self, make, model, year):
#初始化描述汽车的属性
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0 #添加一个名为odometer_reading的属性，初始值为0
def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name
def read_odometer(self):
#打印一条指出汽车里程的消息
print('this car has ' + str(self.odometer_reading) + ' miles on it')
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.odometer_reading = 23#直接修改
my_new_car.read_odometer()
2016 audi a4
this car has 23 miles on it
================================
#通过方法修改属性的值
class Car():
def __init__(self, make, model, year):
#初始化描述汽车的属性
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0 #添加一个名为odometer_reading的属性，初始值为0
def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name
def read_odometer(self):
#打印一条指出汽车里程的消息
print('this car has ' + str(self.odometer_reading) + ' miles on it')
#定义一个新方法
def update_odometer(self, mileage):
#将里程表读数设置为指定的值
self.odometer_reading = mileage
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.update_odometer(23)
my_new_car.read_odometer()
2016 audi a4
this car has 23 miles on it
===========================
#进行扩展
class Car():
def __init__(self, make, model, year):
#初始化描述汽车的属性
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0 #添加一个名为odometer_reading的属性，初始值为0
def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name
def read_odometer(self):
#打印一条指出汽车里程的消息
print('this car has ' + str(self.odometer_reading) + ' miles on it')
#定义一个新方法
def update_odometer(self, mileage):
#将里程表读数设置为指定的值,禁止将里程表往回调
if mileage >= self.odometer_reading:
self.odometer_reading = mileage
else:
print('you can not roll back an odometer')
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.update_odometer(23)
my_new_car.read_odometer()
===================================
#通过方法对属性的值进行递增
class Car():
def __init__(self, make, model, year):
#初始化描述汽车的属性
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0 #添加一个名为odometer_reading的属性，初始值为0
def get_descriptive_name(self):
long_name = str(self.year) + ' ' + self.make + ' ' + self.model
return long_name
def read_odometer(self):
#打印一条指出汽车里程的消息
print('this car has ' + str(self.odometer_reading) + ' miles on it')
def update_odometer(self, mileage):
#将里程表读数设置为指定的值
self.odometer_reading = mileage
def increment_odometer(self, miles):
#将里程表读数增加指定的量
self.odometer_reading += miles
my_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())
my_new_car.update_odometer(23500)
my_new_car.read_odometer()
my_new_car.increment_odometer(100)
my_new_car.read_odometer()
2016 audi a4
this car has 23500 miles on it
this car has 23600 miles on it
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