current position：Home>A glance at Python's file processing (Part 1)
A glance at Python's file processing (Part 1)
2022-01-31 12:45:31 【Lei Xuewei】
「 This is my participation 11 The fourth of the yuegengwen challenge 10 God , Check out the activity details ：2021 One last more challenge 」
ceremonial Python Column No 34 piece , Classmate, stop , Don't miss this from 0 The beginning of the article ！
A lot has been written before , Are doing some data processing , But when we need to store and read data , You need documents . The school committee took you through file processing .
For example, when I was at school , The design requirement of the first programming course is to make a student management system .
This requires the use of files to handle （ You can also use a database , But in general C Language is the preferred language for many freshmen in computer department , At this time, the probability does not know the database ）.
python The most common is open and write function , as follows ：
#open function ： Receive a file name , There are other parameters that can be omitted . one_file = open('myfile.txt') # Read data assigned to data Variable data = one_file.read() # Of a file object write function one_file = open('myfile.txt','w') #write function ： Incoming data ,write Function writes data to one_file In the corresponding file . one_file.write(' Data written to a file ') Copy code
Let's take a look at some examples of file operations
Read file data
Keep the following data as a file ：sample.txt
Continuous learning Continuous development My name is Lei Xuewei Copy code
afile = open("sample.txt") print(afile.read()) Copy code
Write data and simply display
#!/usr/bin/env python # -*- coding: utf-8 -*- # @Time : 2021/11/12 11:58 Afternoon # @Author : LeiXueWei # @CSDN/Juejin/Wechat: Lei Xuewei # @XueWeiTag: CodingDemo # @File : filedemo.py # @Project : hello afile = open("sample.txt") data = afile.read() print("sample file content=", data) afile.close() # hold sample The read data is written to test file afile = open("./test.txt", "w") afile.write(data) afile.close() print("write data to test file!") afile = open("./test.txt") data = afile.read() afile.close() print("test file content=", data) Copy code
Let's see , The read content is indeed written .
The operation of this file is very simple .
Reading and writing files is so simple , But after we manipulate the file , Remember to call close function （ Close file , Otherwise, exceptions will occur in subsequent read / write operations / error ！）
close The function is called as follows ：
one_file.close() # File object .close() Copy code
But we usually write this style of file reading and writing ：
with open('sample.txt', 'r') as one_file: data = one_file.read() # No need to call close 了 , This with Within code block ,python Will help us automatically close the file . Copy code
All the above are read at one time as soon as you open the file ,Python You can also read line by line .
According to the line read / Write data by line
According to the line read
We modified the code based on the previous read-write file , Look directly at ：
#!/usr/bin/env python # -*- coding: utf-8 -*- # @Time : 2021/11/12 11:58 Afternoon # @Author : LeiXueWei # @CSDN/Juejin/Wechat: Lei Xuewei # @XueWeiTag: CodingDemo # @File : filedemo2.py # @Project : hello with open("sample.txt") as afile: data = afile.readline() print("sample file content=", data) with open("./test.txt", "w") as afile: afile.write(data) print("write data to test file!") with open("test.txt") as afile: data = afile.readline() print("test file content=", data) Copy code
We see here reading sample One line of the file , Then write to test file , There is only one line ！
Python The reading of files is very convenient , Built in open Functions and file objects come with write function , The design is very simple .
Open the box , So simply knock , Take a few minutes to learn some file operations ！
by the way , like Python Friend, , Please pay attention to Python Basic column or Python From getting started to mastering the big column
Continuous learning and continuous development , I'm Lei Xuewei ！
Programming is fun , The key is to understand the technology thoroughly .
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author[Lei Xuewei],Please bring the original link to reprint, thank you.
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