Case Change Operations for Strings

There are some methods in Python which are commonly used to normalize string inputs, to convert strings to uppercase or lowercase, and to capitalize the first letter of a sentence or word. These methods can be particularly useful when dealing with user input or when working with text data that needs to be standardized or formatted consistently.

String to lowercase

The lower() and upper() methods are used to convert all the characters in a string to lowercase and uppercase, respectively.

The lower() method converts all uppercase characters in the string to their lowercase equivalents, while leaving any existing lowercase characters unchanged. The method has the following syntax:

string.lower()

Here, string is the original string to be converted to lowercase. The method returns a new string with all the uppercase characters converted to lowercase.

For example, consider the following code snippet:

string = "Hello World"
new_string = string.lower()
print(new_string) # Output: hello world

In this example, the lower() method is used to convert all the uppercase characters in the string variable to lowercase. The resulting lowercase string is then printed out using the print() function.

String to uppercase

Similarly, the upper() method converts all lowercase characters in the string to their uppercase equivalents, while leaving any existing uppercase characters unchanged. The method has the following syntax:

string.upper()

Here, string is the original string to be converted to uppercase. The method returns a new string with all the lowercase characters converted to uppercase.

For example, consider the following code snippet:

string = "Hello World"
new_string = string.upper()
print(new_string) # Output: HELLO WORLD

In this example, the upper() method is used to convert all the lowercase characters in the string variable to uppercase. The resulting uppercase string is then printed out using the print() function.

Capitalize a string in Python

The capitalize() method only capitalizes the first letter of the string, and leaves the rest of the letters in lowercase. Here's an example:

string = "hello world"
capitalized_string = string.capitalize()
print(capitalized_string) # Output: Hello world