Python lowercase: A comprehensive guide in 2023 

In this tutorial, we will learn about python lowercase. We will understand how to perform the lowercase operation in python. so let’s get started.

Introduction to python lowercase

Python has an inbuild function called lower() which is used to perform the lowercase operation in python. The lower () function will convert all the uppercase letters to the lowercase

Syntax of python lowercase

The lower() function in python follows the below syntax


The lower() function does not takes any parameter and returns the lowercase string from the given string.

Python convert a string to lowercase

Let’s take a string and try to convert it into lowercase using the lower() function.

b = a.lower()

The above code prints the string in lowercase

Python lowercase

The .lower() function converts all occurrences of uppercase to lower as shown below

a = "STRinG To bE LoWEr"
b = a.lower()
Python convert a string to lowercase

Python lowercase list

The .lower() function can also be used to convert the element present in the list into lowercase. Let’s take the below example.

l = ["JOHN","JACK","HARRY"]
l_lower = [x.lower() for x in l]

we use the lower function to loop through the entire list and convert the characters to lowercase.

Python lowercase list

Convert textfile to lowercase

So far we have seen how to convert a string or list into lowercase. In this session, we will understand how to convert the case of all characters in a textfile.

Below is the content of a textile name test_file.txt

Convert textfile to lowercase

Let’s use the below code to convert all characters to lowercase.

## Read the content of file
with open('./test_file.txt', 'r') as input_file:
    # open another file to write to in append mode
    with open('./test_file_lower.txt', 'a') as output_file:
        # read each line from input file
        for line in input_file:
            # change case for the line and write
            # it into output file

We use the open function to open two files, one to read from and the other to write to. While writing each line to the output file we are applying the lower() function.

Check the content of the output file to verify the data.

Convert textfile to lowercase


I hope you have liked this small tutorial about python lowercase. Please do let me know if you need any more input.

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