> 类
* `c1.py `文件
```
class Student():
name = ""
age = 24
def getInfo(self):
print("name "+self.name)
print("age "+str(self.age))
stud1 = Student()
stud2 = Student()
stud3 = Student()
# stud1.getInfo()
print(id(stud1)) # 2825425418392
print(id(stud2)) # 2825425418560
print(id(stud3)) # 2825425418728
```
* `c2.py `文件，类的调用
```
from c1 import Student
stru = Student()
print(stru) # <c1.Student object at 0x000002703928CF60>
```
> 构造函数
* `c3.py `文件
```
class Student():
def __init__(self):
print("init")
```
* 打印构造函数
```
stru = Student()
a = stru.__init__()
print(a) # None
print(type(a)) # <class 'NoneType'>
```
* 返回值，只能返回 `return None`，不能返回其他
```
def __init__(self):
return None
```
* 类变量和实例变量
```
s1 = Student("Tinywan",24)
s2 = Student("TinyAiAI",22)
print(s1.name)
print(s2.name)
print(Student.name)
```
* 类和实例的字典`__dict__`
```
s1 = Student("Tinywan",24)
print(s1.__dict__) # 保存当前对象所有的变量和方法
```
* 访问类属性的两种方法
```
class Student():
age = 24
sum = 100
def __init__(self,name,age):
self.__class__.sum += 1 # 操作
print(self.__class__.sum) # 第一种
print(self.age) # 第二种
```
