Python3中级主题快速入门

经过python的基础, 你将有兴趣进一步了解Python3编程语言的更多高级主题。
本文介绍了它们。
请记住, Python完全适用于缩进, 建议你通过运行某些程序进行一些练习。使用Tab键为你的代码提供缩进。
本文分为以下五个部分：
类就像其他所有面向对象的编程语言一样, Python也支持类。让我们看一下关于Python类的几点。

类由关键字创建类.
属性是属于类的变量。
属性始终是公共属性, 可以使用点(.)运算符进行访问。例如：Myclass.Myattribute

类示例：

# creates a class named MyClass class MyClass: # assign the values to the MyClass attributes number = 0 name = "noname"def Main(): # Creating an object of the MyClass. # Here, 'me' is the object me = MyClass() # Accessing the attributes of MyClass # using the dot(.) operator me.number = 1337 me.name = "Harssh"# str is an build-in function that # creates an string print (me.name + " " + str (me.number))# telling python that there is main in the program. if __name__ = = '__main__' : Main()

输出：

Harssh 1337

方法
方法是一堆旨在在你的Python代码中执行特定任务的代码。

属于一个类的函数称为方法。
所有方法都需要’ 自’ 参数。如果你使用其他OOP语言进行编码, 则可以将” self” 视为用于当前对象的” this” 关键字。它会取消隐藏当前实例变量。” self” 的工作方式通常类似于” this” 。
” def” 关键字用于创建新方法。

# A Python program to demonstrate working of class # methodsclass Vector2D: x = 0.0 y = 0.0# Creating a method named Set def Set ( self , x, y): self .x = x self .y = ydef Main(): # vec is an object of class Vector2D vec = Vector2D()# Passing values to the function Set # by using dot(.) operator. vec. Set ( 5 , 6 ) print ( "X: " + str (vec.x) + ", Y: " + str (vec.y))if __name__ = = '__main__' : Main()

输出：

X: 5, Y: 6

遗产
继承是指特定类从其基类继承要素的一种方式。基类也称为” 超类” , 而从超类继承的类称为” 子类”

文章图片
如图所示, 派生类可以从其基类继承要素, 也可以定义自己的要素。

# Syntax for inheritanceclass derived - classname(superclass - name)

# A Python program to demonstrate working of inheritance class Pet: #__init__ is an constructor in Python def __init__( self , name, age): self .name = name self .age = age# Class Cat inheriting from the class Pet class Cat(Pet): def __init__( self , name, age): # calling the super-class function __init__ # using the super() function super ().__init__(name, age) def Main(): thePet = Pet( "Pet" , 1 ) jess = Cat( "Jess" , 3 )# isinstance() function to check whether a class is # inherited from another class print ( "Is jess a cat? " + str ( isinstance (jess, Cat))) print ( "Is jess a pet? " + str ( isinstance (jess, Pet))) print ( "Is the pet a cat? " + str ( isinstance (thePet, Cat))) print ( "Is thePet a Pet? " + str ( isinstance (thePet, Pet))) print (jess.name)if __name__ = = '__main__' : Main()

输出：

Is jess a cat? True Is jess a pet? True Is the pet a cat? False Is thePet a Pet? True Jess

迭代器
迭代器是可以迭代的对象。

Python使用__iter __()方法返回该类的迭代器对象。
然后, 迭代器对象使用__next __()方法获取下一项。
引发StopIteration Exception时, for循环停止。

# This program will reverse the string that is passed # to it from the main function class Reverse: def __init__( self , data): self .data = http://www.srcmini.com/data self .index = len (data)def __iter__( self ): return selfdef __next__( self ): if self .index = = 0 : raise StopIteration self .index - = 1 return self .data[ self .index]def Main(): rev = Reverse('Drapsicle' ) for char in rev: print (char)if __name__ = = '__main__' : Main()

【Python3中级主题快速入门】输出：

e l c i s p a r D

发电机

创建迭代器的另一种方法。
使用函数而不是单独的类
生成next()和iter()方法的后台代码
使用一个称为yield的特殊语句, 该语句保存生成器的状态并为再次调用next()时设置一个恢复点。

# A Python program to demonstrate working of Generators def Reverse(data): # this is like counting from 100 to 1 by taking one(-1) # step backward. for index in range ( len (data) - 1 , - 1 , - 1 ): yield data[index]def Main(): rev = Reverse( 'Harssh' ) for char in rev: print (char) data = 'http://www.srcmini.com/Harssh' print ( list (data[i] for i in range ( len (data) - 1 , - 1 , - 1 )))if __name__ = = "__main__" : Main()

输出：