str.lower() Function in Python

The str.lower() function in Python is used to convert all uppercase letters in a string to lowercase. Non-alphabetical characters (such as digits, punctuation, and spaces) remain unaffected.

Syntax:

string.lower()

• string: The string that you want to convert to lowercase.

Example:

# Example 1: Convert a string to lowercase
my_string = "HELLO, WORLD!"
lowercase_string = my_string.lower()
print(lowercase_string)  # Output: "hello, world!"

In this example:

• The string "HELLO, WORLD!" is converted to "hello, world!".
• Only the uppercase letters are converted to lowercase, while punctuation and spaces are unaffected.

Example with mixed case:

# Example 2: Mixed case string
mixed_string = "Python Is Fun!"
lowercase_mixed = mixed_string.lower()
print(lowercase_mixed)  # Output: "python is fun!"

Here, the uppercase letters in "Python Is Fun!" are converted to lowercase, and other characters (like spaces and punctuation) remain unchanged.

Example with numbers and special characters:

# Example 3: String with numbers and special characters
special_string = "123ABC!@#"
lowercase_special = special_string.lower()
print(lowercase_special)  # Output: "123abc!@#"

In this case:

• The digits (123) and special characters (!@#) are not affected.
• The uppercase letters (ABC) are converted to lowercase (abc).

Key Points:

• str.lower() affects only alphabetic characters and converts them to lowercase.
• It does not modify the original string but returns a new string with the converted characters.
• Non-alphabetic characters like numbers, punctuation, and spaces remain unchanged.