Fourth day of basic Python learning

Source: Internet
Author: User

4.1 Encoding and decoding

4.2 File operations



8th Day of self-study, title arranging study fourth day


Encode encoding

Docode Decoding


Python2 default ASCII format

#-*-Coding:utf-8-*-# What is the code format for declaring a program


# decode text into Unicode format

sname = Name.decode ("Utf-8") # must first declare what the decoded format is, such as Utf-8print (sname) ssname = Sname.encode ("GBK") # encode text into GBK format print (ssname)

# It must be noted that when GBK turns into Utf-8, it must first be converted to Unicode and then to Uft-8, and vice versa.


Python3 default Unicode


b = byte = byte type = 2 binary



Py3 and Py2 Coding differences

Encode the data into the bytes type while coding

Decode the bytes type into a string while decoding


The method that can be called must be an object


File operations, the following methods are used in the file Operation object

R: Read mode operation

W: Write Action Object

A: Append add

r+: Read- write mode when you use write, the text is appended to the end of the last line

w+: Write mode when you use write, the contents of the file are emptied before being written to the file

A +: Additional Reading

Open (1)# on, 1 means one character is printed only

Close# closing files

Write# writing mode


RA = open (' Test file ', ' W ', encoding= ' utf-8 ')

Ra.write ("is the first line to test the string.")

Print (RA)

Ra.close ()

Print Result: <_io. Textiowrapper name= ' test file ' mode= ' W ' encoding= ' Utf-8 ' >


RA = open (' Test file ', ' R ', encoding= ' utf-8 ')

rar = Ra.read ()

Print (RAR)

Ra.close ()

Print Result: Is the first line to test the string.


RAA = open (' Test file ', ' a ', encoding= ' utf-8 ')

Raa.write (' is the second line test string ')

Raa.close ()

Hit this text result: is the first line to test the string. That's the second line. The test string is not wrapped by default, and the default insertion is at the cursor


RAA = open (' Test file ', ' a ', encoding= ' utf-8 ')

Raas = Raa.write (' \ n is the second line test string \ n ')

Raa.close ()

Unlike the previous one, it wraps after the line break


File Operation Flow:

1, open the file, get the file handle and assign value to a variable;

Handle: The Action object of the file

2, through the handle to the file operation;

3. Close the file


ReadLine () Print line default first row

ReadLines () Print all Lines

# Open a test file in a read-only manner, formatted as Utf-8file = open (' Test file ', ' R ', encoding= ' Utf-8 ') # Assign a file variable a = File.readlines () # set an initial value nubmer=0# Loop to print the value of the A-file variable, starting with the first for I in a:# initial value every time you add 1 to 2, use join to change the configuration item to this line, do not print the/n newline character nubmer+=1 if Nubmer = = 2:i = ". Join ([ I.strip (), ' AAAAA ') # Every time this line is printed, when the 2nd time equals join then output the value of the 2nd time variable print (I.strip ()) # Close the file Operation properties, A.close ()

Modify a file

# define two variables and files

F_read = open (' Test file ', ' R ', encoding= ' utf-8 ')

F_write = open (' Test file 2 ', ' W ', encoding= ' utf-8 ')

Number = 0# Sets the variable to 0 loops for a file line, each time adding 1for f in F_read:number + = 1 if numbers = = 2:# When 2 o'clock, assign a f= ' Xiong test to the file variable string. \ n ' F_write.write (f) # finally write it to a new file, you can complete the change file operation

# to manage a single object, this method no longer needs to use the close () method

With open (' Test file ', ' R ', encoding= ' utf-8 ') as F1:

Pass


# Manage Multiple objects

With open (' Test file ', ' R ', encoding= ' Utf-8 ') as F1,open (' Test file 2 ', ' W ', encoding= ' Utf-8 ') as F2:

Pass


Tell detect cursor Position

Print (File.read (4))

Print (File.tell ())

Print Result: is the first

3 characters in Chinese, uft8 format


The file object. Seek () adjust the cursor position

Print (File.seek (1))

Print (File.tell ())

Printed results: 1

1


Flush: Data is removed from the cache and stored synchronously with the disk


Import Sys,time

Sys.stdout.write ("*")


# truncation is done in write mode, must use Write,append format

Truncate # empty file contents


Fileno# File descriptor


Isatty# to see if it's an end device


This article is from the "Xiong" blog, make sure to keep this source http://xiong51.blog.51cto.com/5239058/1964168

Fourth day of basic Python learning

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.