Article directory
1. Read the file
1. Use the for loop to read the file
Use the for loop to read the file, and each loop assigns a line of data in the file to a temporary variable. The syntax is as follows:
for 临时变量 in 文件对象:
# 每次循环都将一行数据赋值给临时变量
# 每次对读取的一行数据进行操作
Code example:
"""
文件操作 代码示例
"""
file = open("file.txt", "r", encoding="UTF-8")
print(type(file)) # <class '_io.TextIOWrapper'>
print("使用for循环读取文件: ")
for line in file:
print(line)
Results of the :
D:\001_Develop\022_Python\Python39\python.exe D:/002_Project/011_Python/HelloPython/Hello.py
<class '_io.TextIOWrapper'>
使用for循环读取文件:
Hello World
Tom
Jerry
Process finished with exit code 0
2. Close the file
1. close function
Call the file object #close function to close the file object;
Close the file object, you can close the program's occupation of the file;
If the file is not closed and the program keeps running, the file will be occupied by the program all the time, and other applications or this application cannot access the file normally;
Close file syntax:
文件对象.close()
Two ways to release file occupation:
- Call the file object #close() function to release the file occupation;
- Killing the application process occupied by the file can also release the file occupation;
2. Code example - file is occupied
Example of file usage:
"""
文件操作 代码示例
"""
import time
file = open("file.txt", "r", encoding="UTF-8")
print(type(file)) # <class '_io.TextIOWrapper'>
print("使用for循环读取文件: ")
for line in file:
print(line)
# 休眠 1000 秒
time.sleep(1000)
In the above code, after the file reading operation is completed, it sleeps for 1000 seconds and keeps the program from exiting. At this time, the file will be occupied all the time. If you try to delete the file in the file manager, the following error will be reported;
3. Code example - close the file
Code example:
"""
文件操作 代码示例
"""
import time
file = open("file.txt", "r", encoding="UTF-8")
print(type(file)) # <class '_io.TextIOWrapper'>
print("使用for循环读取文件: ")
for line in file:
print(line)
# 关闭文件
file.close()
Results of the :
D:\001_Develop\022_Python\Python39\python.exe D:/002_Project/011_Python/HelloPython/Hello.py
<class '_io.TextIOWrapper'>
使用for循环读取文件:
Hello World
Tom
Jerry
123
Process finished with exit code 0
3. The with open syntax automatically handles file closing
1. with open syntax
Use the with open syntax to open the file, which can automatically close the file operation, avoiding the problem of file occupation caused by negligence;
Grammar description:
with open(文件路径, 打开模式) as 文件对象:
在该语句块中借助文件对象操作文件
操作完毕后不需要手动关闭文件
会自动将文件对象关闭
2. Code example - with open syntax example
Code example:
"""
文件操作 代码示例
"""
import time
with open("file.txt", "r", encoding="UTF-8") as file:
print("使用for循环读取文件: ")
# 读取文件
for line in file:
print(line)
# 休眠 1000 秒避免程序退出, 用于测试文件是否被占用
time.sleep(1000)
Results of the :
D:\001_Develop\022_Python\Python39\python.exe D:/002_Project/011_Python/HelloPython/Hello.py
使用for循环读取文件:
Hello World
Tom
Jerry
123
Try to rename the file.txt file to file1.txt, the renaming is successful, indicating that the file is not occupied;
