Python First day course

1, write a Python script under Linux, the beginning of the interpreter declaration should be #!/usr/bin/env python

Define variable name= "Liubo" age=21 all quotes are strings

The meaning of the variable is to indicate the data, so the variable name should make sense

Complex variable names are encountered using "_" to split multiple words or capitalize the first letter of a word

Son_of_twins_brother_age = 2

NAMEOFTWINSGF = "Fengjie"

You cannot use "-" to connect words

You cannot start with a number

You cannot use special characters

There can be no spaces in variable names

You cannot use a keyword as a variable

In Python2. X is supported by default ASCII encoding, if required in Chinese need to explicitly indicate the encoding table, the wording is:

#！ /usr/bin/env python

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

Python3 uses UTF-8 encoding by default, so no special announcements are required, only

#！ /usr/bin/env Python is used to declare an interpreter (Linux runs)

Python development specification, maximum of 80 characters per line

Comments

#用于单行注释

Use 3 quotation marks (three each before and after) for multiple lines of comment

‘‘‘

Xxx

Xxx

‘‘‘

Print user-entered content

The notation in 3.0

User_input = input ("Input your Name:")

Print ("User input msg:", User_input)

The notation in 2.7

User_input = raw_input ("Input your Name:")

Print ("User input msg:", User_input)

In 2.7, input will assume that you are not entering a string, but a variable name, so if you want to pay the input to the variable, you should use Raw_input. Otherwise it will be an error

But if input is a number, it will be considered a number. So in 2.7, input can be a number, or it can be a variable name, and if it is a string, only raw_input

Therefore, the 2.7 basic does not use input

formatting strings

#!/usr/bin/envpython

#_ *_coding:utf-8_*_

Name=input ("Inputyourname:")

Age=input ("Inputyourage:")

Job=input ("Inputyourjob:")

Msg= ""

informationforuser:%s

-----------------------

name:%s

age:%s

job:%s

-----------END------------

"% (name,name,age,job) #% has spaces before and after

Print (msg)

%s represents a string and can be substituted with%d for the number entered

However, if you want to use%d, you must make sure that the variable is a numeric type and that input is a string type, so the age variable cannot use%d directly, and the input is converted to the INT type

That

Age=int (Input ("Input your Age:"))

Name=input ("Inputyourname:")

Age=int (Input ("Inputyourage:"))

Job=input ("Inputyourjob:")

Msg= ""

informationforuser:%s

-----------------------

name:%s

age:%d

job:%s

-----------END------------

"% (name,name,age,job) There are spaces before and after #%

Print (msg)

The formatted data type has 3

$s string

$d numbers

$f Decimals

Import module (the imported content can only be used under Windows CMD or Linux, Pycharm is not available)

Import Getpass #导入一个可以使输入变成密文的模块

Username = input ("Username:")

Password = getpass.getpass ("Password:")

Import OS #导入系统命令模块

Os.system ("DF") #用于打印系统命令

Os.mkdir ("/root/123") #用于创建一个文件夹

Os.system ("df-h") the output of this command is 2, one is the actual command output, one is the output, the command output is the content of DF (System storage usage), the output is 0

If we direct cmd = Os.system ("Df-h"), then only the output in cmd, if you want to copy the command output should be written as

cmd = Os.popen ("Df-h"). Read (), first save the results in memory with Popen, and then read

The module that follows the actual import command is a Python script, but cannot take a. py suffix

However, the location of this script needs to be noted, by default the system looks for a script under a specific path, or under the current path. The method for finding a specific path is

Import Sys

Print (Sys.path)

>>> Import Sys

>>> Print (Sys.path)

[', '/usr/local/python3/lib/python35.zip ', '/usr/local/python3/lib/python3.5 ', '/usr/local/python3/lib/python3.5 /plat-linux ', '/usr/local/python3/lib/python3.5/lib-dynload ', '/usr/local/python3/lib/python3.5/site-packages ']

You can see from here that the first seat is ', so the current path is the highest priority, so if there is a script with the same name in another path under the current path, the current path takes precedence

We can write a module on our own, using the previous

Import Getpass

Username = input ("Username:")

Password = getpass.getpass ("Password:")

Print (Username,password)

Save it as pass.py, then save it to the path above, and then import the pass in the other script to get the module imported.

If judgment

Python is a language with strong formatting and its syntax is formatted according to strict indentation

User= "Liubo"

Passwd= "Cisco,123"

Username=input ("inputyourusername;")

Password=input ("Inputyourpassword:")

If user = = Username:

Print ("Usernameiscorrect ...")

if passwd = = password:

Print ("Welcomelogin ...")

Else

Print ("Passwordisinvalid ...")

Else

Print ("Usernameisinvalid")

At the same time, if can be judged by multiple conditions

User= "Liubo"

Passwd= "Cisco,123"

Username=input ("inputyourusername;")

Password=input ("Inputyourpassword:")

If User==username and Passwd==password:

Print ("Welcome login")

Else

Print ("Usernameorpassworisinvalid")

Cycle

For I in range: Range (10) represents 10 numbers from 0 to 9

Loop 10 times, but guess 3 times, more than 3 times automatically jump out

Age=32

Foriinrange (10):

Ifi<3:

Gage=int (Input ("Inputage:"))

Ifgage>age:

Print ("Guessmorethanage")

Elifgage<age:

Print ("Guesslessthanage")

Else

Print ("Yougotit")

Break

Else

Print ("Toomanytimes")

Break

For I in range (10)

i=100

In the above content, range (10) represents a sequence, so in the for loop each time I is the value of the sequence is assigned value, even if the following re-assignment, as long as it is still in this loop, the I will still be covered by the range

Jump out of programs

1, jump out of the entire program, break, set to complete, when running to break, will end the program

2, jump out when the cycle, continue, set to complete, when running to continue, will end when the second cycle, but the overall cycle will still have

Job One: Blog

Job Two: Writing a login program

Enter User name password

Show welcome message after successful authentication

Three-time error after locking

Job Three: Multilevel menu

1. Beijing

2. Shanghai

>>input

1. Dongcheng

2. Xicheng

>>input

1. Shahe

>>input

Enter b at the same time to return to the parent menu, Q exit Program

Flowchart processon.com

Readme:

Svn:

Job Naming Day1

Python First day course