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This article focuses on "how to use Python to read text files line by line", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Now let the editor take you to learn how to read text files line by line with Python.

What is the open () function in Python?

If you want to read a text file in Python, you must first open it.

This is the basic syntax of the open () function of Python:

Open ("name of file you want opened", "optional mode") file name and correct path

If the text file is in the same directory (folder) as your current file, you only need to reference the file name in the open () function.

Open ("demo.txt")

If your text file is in a different directory, you need to reference the correct pathname of the text file.

In this example, the random-text file is in a different folder, and then main.py:

In order to access the file in main.py, you must include the folder name in the file name.

Open ("text-files/random-text.txt")

If you do not have the correct file path, you will receive the following error message:

Open ("random-text.txt")

It is important to keep track of your directory so that you can reference the correct pathname.

Optional mode parameter open ()

There are different modes when working with files. The default mode is read mode.

The letter r stands for reading mode.

Open ("demo.txt", mode= "r")

You can also omit mode= and just write "r".

Open ("demo.txt", "r")

There are other types of patterns, such as "w" for writing or "a" for attaching. I won't go into the other patterns in detail, because we will only focus on reading files.

Additional parameters of functions in open () Python

The open () function accepts these optional parameters.

Buffering

Encoding

Errors

Newline

Closefd

Opener

What is the readable () method in Python?

If you want to check that the file is readable, you can use the readable () method. This will return a True or False.

This example will return True because we are in read mode:

File = open ("demo.txt") print (file.readable ())

If I change this example to "w" (write) mode, the readable () method will return False:

File = open ("demo.txt", "w") what is the read () method in print (file.readable ()) Python?

The read () method reads all the contents of the file as a string. This is a good way to do this if there is not much content in the text file.

In this example, I use the read () method to print a list of names from the demo.txt file:

File = open ("demo.txt") print (file.read ())

This method can receive an optional parameter named size. Instead of reading the entire file, only part of it is read.

If we modify the previous example, we can print out only the first word by adding the number 4 as a parameter to read ().

File = open ("demo.txt") print (file.read (4))

If the size parameter is omitted, or if the number is negative, the entire file is read.

What is the close () method in Python?

When you are finished reading the file, it is important to close it. If you forget to close the file, it may cause problems.

This is an example of how to close the demo.txt file:

File = open ("demo.txt") print (file.read ()) file.close () withPython how to use keywords to close files

One way to ensure that the file is closed is to use the with keyword. This is considered a good practice because the file closes automatically, and you don't have to close it manually.

Here is how to rewrite our example using the with keyword:

With open ("demo.txt") as file: what is the readline () method in print (file.read ()) Python?

This method reads a line from the file and returns.

In this example, we have a text file that contains these two sentences:

This is the first lineThis is the second line

If we use the readline () method, it only prints the first sentence of the file.

With open ("demo.txt") as file: print (file.readline ())

This method also accepts optional size parameters. We can modify the example to add the number 7 to read and print out only the This is:

With open ("demo.txt") as file: what is the readlines () method in print (file.readline (7)) Python?

This method reads and returns a list of all lines in the file.

In this example, we will use the readlines () method to print the grocery items as a list.

With open ("demo.txt") as file: print (file.readlines ()) how to read lines from a file in Python using a for loop

The alternative to these different reading methods is to use for loop.

In this example, we can demo.txt to print out all the items in the file by looping the object.

With open ("demo.txt") as file: for item in file: print (item) conclusion

If you want to read a text file in Python, you must first open it.

Open ("name of file you want opened", "optional mode")

If the text file is in the same directory (folder) as your current file, you only need to reference the file name in the open () function.

If your text file is in a different directory, you need to reference the correct pathname of the text file.

The open () function accepts optional mode parameters. The default mode is read mode.

Open ("demo.txt", "r")

If you want to check that the file is readable, you can use the readable () method. This will return a True or False.

File.readable ()

The read () method reads all the contents of the file as a string.

File.read ()

When you are finished reading the file, it is important to close it. If you forget to close the file, it may cause problems.

File.close ()

One way to ensure that the file is closed is to use the with keyword.

With open ("demo.txt") as file: print (file.read ())

The readline () method reads a line from the file and returns.

File.readline ()

The readlines () method reads and returns a list of all lines in the file.

File.readlines ()

The alternative to these different reading methods is to use for loop.

With open ("demo.txt") as file: for item in file: print (item) so far, I believe you have a better understanding of "how to read text files line by line with Python". You might as well do it in practice! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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