Python

I. Database connection poolpython programming can use MYSQLDB for database connection and operations such as query, insert, UPDATE, but each time the MySQL database request, are independent to request access, quite a waste of resources, and access

First download the requests library from GitUnzip, put into the Python installation directory, select Requests Library, Shfit right mouse button, enter cmd, input python setup.py install, after running, enter import requests detect whether the

Django-model FoundationCreation of tables (model building)Example 1: fromDjango.dbImportModels#BooksclassBook (models. Model): ID=models. Autofield (primary_key=True) Title=models. Charfield (max_length=32) PubDate=models. Datefield () Price=models.

The Shopping Cart Program sub-module programming, shopping cart 1 wrote the login section, the following rewrite the shopping section:#!/usr/bin/env pythonProduct_list = [[' Iphone7 ', 5800],[' Coffee ', 30],[' Tea ', 10],[' Python book ', 99],['

Inheritance and polymorphismIn OOP programming, when we define a class, we can inherit from an existing class, the new class is called a subclass (subclass), and the inherited class is called the base class, the parent class, or the superclass (base

Inherited# One of the three main features of object-oriented: inheritance# Inheritance: There are at least two classes: what is the relationship of what, in order to avoid having the same code between several classes# Parent class: Animal#

Can name Meta-ancestor Namedtuplenamedtuple ExampleDeque Dual-ended queuedeque ExampleQueues QueueQueue ExampleAn ordered dictionary (key is kept in order) ordereddictordereddict ExampleWhen using a dictionary, if key does not exist, return a

Data encapsulationAn important feature of object-oriented programming is data encapsulation. In the above Student class, each instance has its own name and score this data. We can access this data through functions, such as printing a student's

One, the system library provides a library of intrinsic function number characters:1) Str.islower (): Whether the strings are all lowercase2) Str.isspace (): Whether the string is empty3) Help (str): query string function library4) str.replace (old,

#!/usr/bin/pytholn#-*-Coding:utf-8-*-Import MathImport SysDef print_13 ():#for I in range (10):man_age = Int (raw_input (' Enter input age:\n '))If Man_age >= and Man_age sex = str (raw_input (' Please input sex:m is the male or F a female and your

Python does not have {} to represent blocks of code, but instead uses indentation to indicate that the Python code was just started, without noticeIndentation, resulting in various errors ((╯-╰))The principle in Python is that the same level of code

Direct Assignment: is actually the object's reference (alias). shallow copy (copy): copies the parent object and does not copy the inner sub-object of the object. deep Copy (deepcopy): The Deepcopy method of the Copy module, which completely

Here we introduce the installation and use of Python's Distributed crawler framework scrapy. mediocre This thing is like the white shirt on the stain, once infected will never wash off, can not be undone. Installation and use of ScrapyMy computer

#文件操作:Read:f = open ("/users/zhouhaijun/python/01.py", "R")x = F.read ()Print XWrite:f = open ("/users/zhouhaijun/python/file_01.py", "WB")F.write ("OK")F.close ()Read:f = open ("/users/zhouhaijun/python/file_01", "R")Text = F.read () #text = f.read

Functional programming: A very high degree of abstraction of the paradigm, the important characteristics: the input is determined, the output is determined;Python is partially supported for functional programming;Higher order functions:def add

Feeling: From the previous thought of OOP design approach to the current expectations, all rely on the book with a game of practice, really do have a feeling, if beginners with simple function to achieve such effects feel incredible, but after this

Multi-process + Semaphore semaphore, process signal Semaphore The following is an example. from multiprocessing import Processfrom multiprocessing import Semaphoreimport datetimeimport timeimport multiprocessingdef worker(s, i): s.acquire()

Python hasattr () getattr () setattr () function Usage Details, hasattrgetattr Hasattr (object, name)Determines whether an object contains the name attribute or name method. The BOOL value is returned. If the object has a name attribute, True is

Python3 file operations (16 ),1. File Operations1. Introduction Computer systems are divided into three parts: computer hardware, operating system, and applications. Applications written in python or other languages must be stored on the hard disk

Python basics 1 and python Basics Variable: Information stored, called, modified, or operated in the future Constant: Fixed amount, all uppercase letters Naming rules: Note: #: Comment on a single line "Or ''': multi-line comment Get user input: