Python Uppercase: A Step-By-Step Guide

The Python upper() method converts all lowercase letters in a string to uppercase and returns the modified string. The Python isupper() returns true if all of the characters in a string are uppercase, and false if they aren’t. Both are useful for formatting data that is dependant on case.

In Python, when you’re working a string, you may want to convert the string to uppercase, or check if the string is already in uppercase.

For example, if you’re creating a program that prepares the data for ticket stubs at a concert, you may want to convert all names to uppercase so that they are easily readable. Before you convert the string to uppercase, you may also want to check if it is already in uppercase.

That’s where the Python upper() and isupper() methods come in. The upper() method can be used to convert all case-based characters in a string to uppercase, and the isupper() method can be used to check if all characters in a string are in uppercase.

We are going to discuss how to use both these methods to work with uppercase strings in this tutorial. We’ll also go through a few examples to illustrate how they work. If you’re interested in learning about lowercase string methods in Python, check out our guide to Python lowercase methods.

Python String Refresher

Strings store text and are typically held in a variable. Strings in Python are declared with single quotes ‘’ or double quotes “”. While both single quotes and double quotes can be used, you should stick to one or the other. Here’s an example of how to declare a string:

string_name = "This is a Python string."

We can print a string with the print() function:

string_name = "This is a Python string."
print(string_name)

Our program returns: This is a Python string.

Now that we’ve brushed up on strings, let’s consider how we can convert them to uppercase.

Python Upper

The built-in Python upper() method can be used to convert all case-based characters within a string to uppercase. The upper() method returns a copy of an original string in which all characters appear in uppercase.

The syntax for the upper() method is as follows:

string_name.upper()

As you can see, the upper() method takes no parameters, and is appended to the end of an existing string value.

Let’s walk through an example to show how the upper() method can be used.

Say that we are working at a movie theater and we are creating a program that converts all customer names to uppercase. We are doing this so that customer names are easily readable on tickets and use a consistent case, which will make it easier for the movie clerks to check the identity of moviegoers.

To accomplish this task, we could use the upper() method. Here’s an example of the upper() method being used to convert a string to uppercase:

attendee_name = "Elsie Swanson"

print(attendee_name.upper())

Our code returns: ELSIE SWANSON. Let’s break down our code to show how it works. On the first line, we declare a variable called attendee_name that stores the name of our moviegoer. Then, on the next line, we use upper() to convert attendee_name to uppercase, and then we print the revised name to the console.

The upper() method will not affect symbols, whitespaces, or numbers within a string, because those characters are not case-based.

Python Isupper()

Before you convert a string to uppercase, you may first want to check that the string is not already in uppercase form.

To check if a string is in uppercase, we can use the isupper() method. isupper() checks whether every case-based character in a string is in uppercase, and returns a True or False value depending on the outcome.

Here’s the syntax for the isupper() method:

string_name.isupper()

For instance, let’s use the movie ticket example from above.

Before we convert a moviegoer’s name to uppercase on their ticket, we should first check to see if the name has already been converted to uppercase. This would allow us to make our code more efficient because we would not be converting a string to uppercase that was already formatted in the correct way.

We can do check whether a customer’s name is already in uppercase by using the following code:

attendee_name = "Elsie Swanson"

print(attendee_name.isupper())

Our code returns: False. As you can see, the value of the attendee_name variable is in sentence case. So, when our isupper() method is executed, it returns False, because not every character in the attendee_name variable is in uppercase.

The Python isupper() method returns True if a string includes whitespaces, symbols, or numbers, assuming all case-based characters appear in uppercase.

Python Isupper and Upper

Let’s go a step further with our code. In the above example, we used the isupper() built-in function to check if the customer’s name was already in uppercase.

We could combine both isupper() and upper() to check if a string is already in uppercase, and convert it to uppercase if the string is not already formatted in all-uppercase. Here’s the code we could use to perform this action:

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attendee_name = "Elsie Swanson"

if attendee_name.isupper() == False:
	attendee_name = attendee_name.upper()
	print(attendee_name)
else:
	print("This attendee's name is already in uppercase.")
	print(attendee_name)

The result of our code is as follows:

ELSIE SWANSON

If our attendee_name was already in all-uppercase, our code would return:

This attendee's name is already in uppercase.
ELSIE SWANSON

Let’s break down our code. On the first line, we declare the attendee_name variable which stores the name of our moviegoer. Then, we use an if statement and isupper() to check whether or not the customer’s name is already in uppercase.

If the statement evaluates to False — which means our customer’s name is not in all-uppercase — our program uses the upper() method to convert the customer’s name to uppercase and prints out the revised name to the console.

If the customer’s name is already in upper case, the contents of our else statement are executed, and a message is printed to the console, alongside the name of the attendee.

Conclusion

Working with uppercase strings is a common string operation in Python. The upper() method can be used to convert a string to all-uppercase, and the isupper() method can be used to check whether a string is already in uppercase.

This tutorial discussed how to use both the upper() and isupper() methods to work with uppercase strings in Python. We also explored an example of each of these methods in action, then we discussed how both of these methods can be combined to check if a string is in uppercase, and convert it to uppercase if it is not already in that form.

That’s all you need to know about the upper() and isupper() methods — now you’re ready to use them in your code like a pro in your Python programs!