Python File Handling
Read and write files
Python file handling: create, open, append, read and write
In Python, there is no need to import an external library to read or write files; Python provides a built-in function for creating, writing and reading files.
Related course: Complete Python Programming Course & Exercises
How to create a text file
With Python, you can create various types of files using code such as .txt , .py, etc., with the following code.
Step 1: Create file
f = open("somefile.txt", "w+")
We declare the variable f to open a file named filename.txt. The open method requires two parameters, the file we want to open and a string that indicates the permissions or actions we want to perform on the file
The "w" in the open parameter means write permission, and the "+" text means the file will be created if the piece does not exist.
Step 2: Write data
for i in range(10): f.write("This is line %d\r\n" % (i+1))
Here's a for loop from 1 to 10.
write() function to enter data into a file
Step 3: Close file
Close the instance of the stored file somefile.txt
So to create a new file:
f = open("somefile.txt", "w+") for i in range(10): f.write("This is line %d\r\n" % (i+1)) f.close()
How to append data to a file
Step 1: Open file for appending
When you see the "+" sign in the parameters of the open function, it means that a new file will be created if this file does not exist. But it already has that file in the example, so it does not create a new one.
Step 2: Write data
for i in range(2): f.write("Appended line %d\r\n" % (i+1))
This will be written to the file in an add-on mode.
To append to a file
f.open("somefile.txt", "a+") for i in range(2): f.write("Appended line %d\r\n" % (i+1))
How to read files
Step 1: Open file for reading
Change the second parameter in open to "r"
f = open("somefile.txt", "r")
Step 2: Check if file opened
Use the MODE function to check if the file is in open mode.
if f.mode == 'r'
Step 3: Read data
Use the READ method to read file data and store it in variables
contents = f.read()
Finally, you can print this variable to get the text content in the console
f = open("somefile.txt", "r") if f.mode == 'r' contents = f.read()
How to read a file line by line
If the data is too large, it can be read line by line.
f = open("somefile.txt", "r") f1 = f.readlines for index in f1: print(index)