Python development: First knowledge of Python (note-taking)

Python environment

Python installation

1. Download the installation package

https://www.python.org/downloads/

2. Installation

Default installation path: C:\PYTHONG27

3. Configure Environment variables

"Right-click Computer"-"Properties"-"Advanced system Settings"-"Advanced"-"Environment variables"-"" the Second content box found a row of the variable named path, double-click "-" Python installation directory appended to the variable value, use; Split "

such as: the original value; C:\python27, remember that there's a semicolon in front

Getting Started with Python

One, the first Python code

Create a hello.py file

　　Print "Hello,world"

Second, the Interpreter

To execute a python script, you need to add an interpreter to the file header:

　　　　#!/usr/bin/env python

Print "Hello,word"

Third, Content coding

UTF-8 can be expressed in Chinese, so the switch plus:

#!/usr/bin/env python

　　　　#-*-Coding:utf-8-*-

Print "Hello,world"

Iv. notes

When line comment:# is commented content

Multiline Comment: "" "Annotated Content " ""

V. Execute script incoming parameters

Python itself has a large number of modules, development concise. The class library has three: 1. Internal; 2. Industry open source modules; 3. Programmers develop their own modules

Execution parameters

#!/usr/bin/env python

#-*-Coding:utf-8-*-

　　　　Import sys

Print SYS.ARGV

Vi.. pyc file

When you execute Python code, if you import a different. py file, a . PYc file with the same name is automatically generated during execution, which is the bytecode generated by the Python interpreter after compilation.

PS: Code is compiled to generate bytecode, and bytecode can be obtained by decompile.

Seven, variable

1. Declaring variables

#!/usr/bin/env python

#-*-Coding:utf-8-*-

　　　　Name = "Lzylogo"

Variable definition rules: 1. Can only be any combination of letters, numbers, or underscores; 2. The first character cannot be a number; 3. Keywords cannot be declared as variable names (' and ', ' as ', ' assert ', ' Break ', ' class ', ' Continue ', ' def ', ' Del ', ' elif ', ' Else ', ' except ', ' exec ', ' finally ', ' for ', ' from ', ' global ', ' if ', ' import ', ' in ', ' was ', ' lambda ', ' not ', ' or ' , ' Pass ', ' print ', ' raise ', ' return ', ' try ', ' while ', ' with ', ' yield ')

2. Assigning values to variables

　　#!/usr/bin/env python

#-*-Coding:utf-8-*-

#名字1 = "Lzylogo"

　　　　name1 = "Lzylogo"

#名字2 = "Kitty"

name2 = "Kitty"

#!/usr/bin/env python

#-*-Coding:utf-8-*-

#名字1 = "Lzylogo"

name1 = "Lzylogo"

#名字2 = First Name 1

　　　　Name2 = name1

Eight, input

　　　　Wait for user input

#!/usr/bin/env python

#-*-Coding:utf-8-*-

# Assign user-entered content to the name variable

　　　　Name = Raw_input ("Please enter user name:")

# Print What you have entered

Print Name

　　　　Make password invisible

#!/usr/bin/env python

#-*-Coding:utf-8-*-

# import Getpass Code

Import Getpass

# Assign user-entered content to the name variable

　　　　PWD = Getpass.getpass ("Please enter password:")

# Print What you have entered

Print pwd

Ix. Process Control and indentation

1. User Login Verification

#!/usr/bin/env python

#-*-Coding:utf-8-*-

# Prompt for user name and password

Import Getpass

Name = Raw_input ("Please enter user name")

PWD = Getpass.getpass ("Please enter password")

# Verify user name and password

# If an error occurs, the output user name or password is incorrect

# If correct, just enter "Welcome, kitty"

　　　　If name = = "Lzylogo" and pwd = = "Kitty":

Print "Welcome, kitty"

　　　　Else

Print "User name and password error"

2. export Their permissions based on user input

# kitty--Super admin

# Eric--general manager

# Tony,rain---Business leader

# Other--Ordinary users

Name = Raw_input ("Please enter user name:")

　　　　if name = = "Kitty":

Print "Super admin"

　　　　elif name = = "Eric":

Print "Normal admin"

　　　　elif name = = "Tony" or name = = "Rain"

Print "Business leader"

　　　　Else

Print "Normal user"

Ten, while loop

1. Basic cycle

While condition:

# Loop Body

# If the condition is true, then the loop body executes

# If the condition is false, then the loop body does not perform

2.break for exiting all loops

#代码执行到break那行, the loop exits, and all of the following lines will no longer execute

While True:

Print "123"

Break

Print "456" (exited, will not be executed)

3.continue exits the current loop and continues the next cycle

#代码执行到continue, the current loop is exited and the next loop is executed again

While True:

Print "123"

Continue

Print "456"

Exercise 1: Using while loop input 1 2 3 4 5 6 8 9 10

Start = 1

While True:

　　　　If start = = 7:

Start + = 1

Continue

　　　　　　Print (start)

If start = = 10:

Break

Start + = 1

　　　　　　　　

Python development: First knowledge of Python (note-taking)