Day1-python Learning

Directory

1 Python introduction ... 1

1.1 Current Python main application areas: ... 1

2 Python installation ... 1

2.1 Windows installation ... 1

2.2 Linux installation ... 2

3 python Basic Combat ... 3

3.1 Pycharm Use the shortcut keys ... 3

3.2 Print Hello world. 3

3.3 Python interpreter ... 3

3.4-Character encoding ... 4

3.5 Variable Definition Rules ... 4

3.5.1 Define Variables ... 4

3.5.2 Variable Assignment ... 4

3.6-line Comment ... 5

3.7 User Input ... 5

3.7.1 input password is not visible ... 6

1 Introduction to Python

The founder of Python is Guido van Rossum (Guido van Rossum). During the Christmas of 1989, Guido van Rossum to spend time in Amsterdam, determined to develop a new script interpreter, as an inheritance of the ABC language.

1.1 Current Python main application areas:

• Cloud computing: The hottest language in cloud computing, typically using OpenStack
• Web development: A number of excellent web frameworks, many large sites are Python development, Youtube, Dropbox, watercress ... , a typical web framework has Django
• Scientific computing, Artificial intelligence: Typical library numpy, SciPy, matplotlib, Enthought Librarys,pandas
• System operation and maintenance: the necessary language for operation and maintenance personnel
• Finance: Quantitative trading, financial analysis, in the field of financial engineering, Python is not only used, but also used the most, and the importance of the year. Reason: As a dynamic language Python, the language structure is clear and simple, the library is rich, mature and stable, scientific calculation and statistical analysis are very good, production efficiency is much higher than c,c++,java, especially good at strategy backtesting
• Graphic GUI:PYQT, Wxpython,tkinter

2 Python installation 2.1 Windows installation

Download the installation package www.python.org

Install to C English path

To configure environment variables:

Computer---Properties---advanced system settings---Advanced---environment variables---path[note here is a semicolon-separated]

2.2 Linux Installation

Sohu Download HTTP://MIRRORS.SOHU.COM/PYTHON/3.5.1/website Slow of a lump

wget http://mirrors.sohu.com/python/3.5.1/Python-3.5.1.tgz

Tar XF python-3.5.1.tgz

CD Python-3.5.1

./configure

Make && make install

The installation is complete, the default road strength

/usr/local/bin/python3–v

#可以更改系统默认python版本, it's best to make a soft connection to the/usr/bin/to facilitate the designation interpreter

Ln-s/usr/local/bin/python3/usr/bin/

Mv/usr/bin/python/usr/bin/python2.bak

Ln-s/usr/local/bin/python3/usr/bin/python

3 Python Basic Combat 3.1 pycharm used shortcut keys

Ctrl+d copy a line of content

CTRL +? Bulk Comment Multiple lines

3.2 Print Hello World

Pycharm:

Print ("Hello World")

Windows:

C:\users\lenovo>python

Python 3.4.3 (v3.4.3:9b73f1c3e601, Feb, 22:43:06) [MSC v.1600

TEL)] on Win32

Type "Help", "copyright", "credits" or "license" for more information.

>>>

>>>

>>> print ("Hello World")

Hello World

You can also edit the. py script onto the Windows terminal

C:\users\lenovo>python "C:\Users\lenovo\Desktop\new 1.py"

Linux :

#!/usr/bin/env python

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

Print ("Hello World")

Print ("Hello, World")

3.3 Python Interpreter

Python path can be specified directly

#/usr/bin/python

Specifies the version, which only takes effect after chmod +x, and the default Python test.py only executes the system default Python version.

#/usr/bin/env python

#/usr/bin/env Python3

3.4 Character encoding

python2.x only ASCII is supported by default, Chinese need to declare character set

#!/usr/bin/env python

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

3.5 variable definition rules 3.5.1 Defining variables

Variable names can only be any combination of letters, numbers, or underscores

The first character of a variable name cannot be a number

The following keywords cannot be declared as variable names

Character definition to add "" double quotes

[' and ', ' as ', ' assert ', ' Break ', ' class ', ' Continue ', ' Def ', ' del ', ' elif ', ' Else ', ' except ', ' exec ', ' finally ', ' for ', ' F ' Rom ', ' Global ', ' if ', ' import ', ' in ', ' was ', ' lambda ', ' not ', ' or ', ' pass ', ' print ', ' raise ', ' return ', ' try ', ' while ', ' WI Th ', ' yield ']

3.5.2 Variable Assignment

Day1 = 1000 + 500 + 500

Day2 = 3000

DAY3 = 1000

DAY4 = 4000

Total = day1 + day2 + day3 + day4

Print ("Sum:", total)

Total: 10000

Name = "Zhang"

name2 = Name

Print (name,name2)

Zhang Zhang

3.6-line Comment

Single-line Comment by: #

Multi-line Comments:

• Method One,

"""

Three double quotes annotate multiple lines of content

Three double quotes annotate multiple lines of content

"""

• Method Two,

‘’’

Three double quotes annotate multiple lines of content

Three double quotes annotate multiple lines of content

‘’’

Bulk Comment:

Mouse Check Ctrl +? Implementing bulk Annotations

3.7 User Input

Example 2:

Name = input ("What is your name?")

Print ("Hello", name)

Results:

What is your Name?sdfas

Hello Sdfas

Example 2:\n line break

Name = input ("What is your name?")

# print ("Hello", name)

Job = input ("Job:")

Hobby = input ("Hobby:")

Print ("My name is", Name, "\nmy job was", job, "\nmy hobby is", hobby)

Results:

What is your Name?zh

Job:it

Hobby:it

My name is en

My job is it

My hobby is lol

Example 3:

• Where%s is represented as a character
• Where%d is represented as an integer

Test value

str = "%s"%"Hello"
num = "%d"%33
Print (str)
Print (num)

Name = input ("Whatis your name?")

# print ("Hello", name)

Age =input ("Age:")

Job = input ("Job:")

Hobby =input ("hobby:")

Print ("My Nameis", name, "\nmy job is", job, "\nmy hobby is", hobby)

info = ""

--------Info of%s--------

Name:%s

Age:%s

Jog:%s

Hobby:%s

--------End---------

"% (Name,name,age,job,hobby)

Print (info)

Result: One of the first name is a title

What is your Name?zh

Age:22

Job:it

Hobby:lol

My name is en

My job is it

My hobby is lol

--------info of en--------

Name:zh

Age:22

Jog:it

Hobby:lol

--------End---------

%d integer problem

age = Int (input ("Ages:"))

info = ""

--------Info---------

Age:%d

--------End--------

"% (age)

Print (info)

Results:

Age: 32

--------Info---------

Age:32

--------End--------

Code:

Name = input ("inputyou Name:")

age = Int (input ("Inputyou Age:"))

Print (Type (age), type (name))

Job = input ("Inputyour job:")

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

info = ""

--------------informathionof%s

Name:%s

Age:%d

Job:%s

Salary:%d

--------------End----------

"% (name,name,age,job,salary)

Print (info)

Results:

Input you Name:zhang

Input you age:25

<class ' int ' > <class ' str ' >

Input your Job:it

Input your salary:8888

--------------Informathion of Zhang

Name:zhang

Age:25

Job:it

salary:8888

--------------End----------

Process finished with exit code 0

3.8 If condition statement

conditional expression, after which the condition line is to be followed by: colon, otherwise syntax error

Username =input ("username:")

Password =input ("Password:")

If username = = "Zhang" and password = = "123456":

Print ("Login SUCCESSD")

Else:print ("username Orpassword is worng")

3.8.1 input password is not visible

The Getpass module needs to be defined and the module can only be tested on the server

#!/usr/bin/env python

Import Getpass

PWD =getpass.getpass ("Password:")

Print (PWD)

Results:

[[Email protected] ~] #python test3.py

Password: The password value entered is not visible here

123456

3.9 Guess Age

Oldboy_age = 39

guess_age = Int (Input ("Age:")) #str--INT

If Guess_age ==oldboy_age:

Print ("Correct!!!")

Elif guess_age >oldboy_age: #else if

Print ("Try smaller ...")

Else

Print ("Try bigger ...")

Big guess.

Age:50

Try smaller ...

Process finished withexit code 0

Guess Small

Age:20

Try bigger ...

Process finished withexit code 0

That's right

age:39

Correct!!!

Process finished withexit code 0

3.10 Writing the Login interface

Enter User name password

Show welcome message after successful authentication

Three-time error after locking

Count = 0

Flag = 1

lock = []

User_pass = []

Username =input (' username: ')

F =open (' Heimingdan.txt ', ' R ')

Lock_file =f.readlines ()

F.close ()

For I in Lock_file:

line = I.strip (' \ n ')

Lock.append (line)

If username in Lock:

Print (' Your user%s is already locked please contact admin '%username ')

Else

While True:

Count + = 1

passwd = input ("Password:")

f = open (' Yonghu.txt ', ' R ')

User_file = F.readlines ()

F.close ()

For I in User_file:

Test = 3-(count)

User_pass = I.strip (). Split ()

If username = = User_pass[0] andpasswd = = User_pass[1]:

Print (' Welcome back to%s '%username)

Flag = True

Break

Else

Print (' Password error Please reenter you also have%s chance '%test)

Continue

If flag is True:

Break

Else

if Count = = 3:

Print (' Your user%s is locked, please contact admin '%username)

Lock_file =open (' heimingdan.txt ', ' a ')

Lock_file.write ('%s\n '%username)

Lock_file.close ()

Break

Error

Username:abc

Password:123

Password error Please re-enter you still have 2 chances

password:1234

Password error Please re-enter you still have 1 chances

password:12345

Password error Please re-enter you still have 0 chances

Your user ABC is locked, please contact the Administrator

Success

Username:oldboy

password:123456

Welcome back, Oldboy.

Process finished withexit code 0

Day1-python Learning