Basic concepts and knowledge----python basics

Tidy up the basic concepts and knowledge of Python, mainly using Python3 as the grammar standard.

Python Introduction

An object-oriented interpretive computer design language with rich and powerful libraries.

• Python positioning: "Elegant", "clear", "simple"
• A variety of application scenarios: can write tools, background services, mobile and so on.

Operating Environment construction

Download the corresponding version of the Python installation, the official website address is as follows

https://www.python.org/

Run get-pip.py install Pip (Py3 comes with PIP)

https://bootstrap.pypa.io/get-pip.py

Adding Python directories and scripts subdirectories to environment variables

Install the virtual environment

• Installing Virtualenv

Pip Install Virtualenv

• If configured correctly, it will enter the Python interpreter interface

Python 3.5.2 (V3.5.2:4DEF2A2901A5, June, 22:01:18) [MSC v.1900 + bit (Intel)] on Win32type "help", "copyright", "C Redits "or" license "for more information.>>>

Editor selection

Sublime text,wing Ide,pycharm

basic syntax and Concepts

Variable

>>> x=3>>> x*26>>> x*9992997

　　

Integer, floating-point number

x=567 (integer) y=5.67 (floating-point) x/y (default return floating-point number) x//y (return integer by default)

　　

Function

def checkishascapitalletter (filename):    if filename.islower () = = true:        return True    else:        Common.outerror (filename + "file name in uppercase ...") "Return Fasle" (...)                    

　　

Indentation, flow control statements For,if,while and so on are identified by indentation, and functions are

For I in range (0, 5):    print (i)

Module

>>>import Common (allows the use of namespaces to access things in the common) >>>common.count () >>>from Common import count ( Add to current namespace) >>>count ()

　　

Execute Python Program

Python.exe test.py

Common data structures

• Listing (list)
• Dictionary (dict)
• Collection (SET)
• Tuple (tuple)

Common data types

• Integer
• Floating point number
• Boolean value
• String

String Basics

Strings can not be changed, as in Java, if you assign a value, it is actually a new string

String definition, can be single or double quotes, character stitching with + number

>>> "Hello World", ' Hello World ' >>> ' Hello World ' Hello World ' >>> ' hello ' + ' world ' HelloWorld ' >>> ' don ' t let go ' "Don't let Go" >>> ' don\ ' t let go ' (Escape single quotes) "Don't Let Go" >>> "don\ t let go" "do N ' t let go ">>> r" don\ ' t Let go "(front with" R "not escaped)" don\\ t Let go "

　　

String Lookup

>>> "Nothing is here." Find ("see") 11>>> ' nothing to see here '. Find ("OK")-1

　　

String formatting

>>> filename = "notepad" >>> "Get file:%s OK"%filename ' Get file:notepad OK '

The Unicode,python3 string is a Unicode-encoded
1. Convert other string formats to Unicode:

Ret=str.decode ("gb2312") Ret=str.decode ("ASCII") Ret=str.decode ("Utf-8")

2. Convert Unicode characters to other string formats:

Ret=str.encode ("gb2312") Ret=str.encode ("ASCII") Ret=str.encode ("Utf-8")

Regular expressions

Http://www.cnblogs.com/huxi/archive/2010/07/04/1771073.html

　

Extended

String built-in function, Len (), Split (), Upper (), strip () multi-line string subscript [0],[-2]

　　

Basic concepts and knowledge----python basics