面向对象——类

1认识类-如何定义

• 类最基本作用：封装
• 类下面函数要加self
• 类下面函数变量需要用self引用
• 运行或者调用类要放在外部

class Student():
    name = ''  #定义变量
    age = 0
    def print_file():
        print('name:'+str(age))
student = Student()#完成实例化的过程
student.print_file()#调用类下面方法

报错1

```ruby
D:\pythonProject1\venv\Scripts\python.exe C:\Users\Windows11\Desktop\面向对象\main.py 
Traceback (most recent call last):
  File "C:\Users\Windows11\Desktop\面向对象\main.py", line 7, in <module>
    student.print_file()#调用类下面方法
TypeError: Student.print_file() takes 0 positional arguments but 1 was given

Process finished with exit code 1

需要在类的函数里面加上self固定格式

class Student():
    name = ''  #定义变量
    age = 0
    def print_file(self):
        print('name:'+name)
        print('age:'+str(age))
student = Student()#完成实例化的过程
student.print_file()#调用类下面方法

报错2

D:\pythonProject1\venv\Scripts\python.exe C:\Users\Windows11\Desktop\面向对象\main.py 
Traceback (most recent call last):
  File "C:\Users\Windows11\Desktop\面向对象\main.py", line 7, in <module>
    student.print_file()#调用类下面方法
  File "C:\Users\Windows11\Desktop\面向对象\main.py", line 5, in print_file
    print('name:'+str(age))
NameError: name 'age' is not defined

Process finished with exit code 1

需要加上self关键字

class Student():
    name = ''  #定义变量
    age = 0
    def print_file(self):
        print('name:'+self.name)
        print('age:'+str(self.age))
student = Student()#完成实例化的过程
student.print_file()#调用类下面方法