How To Check If A String Is All Uppercase Python

In this tutorial, we will discuss how to check if a string is all uppercase in Python. This can be useful when you need to validate user input or analyze text. Python has many built-in functions that can be used for string manipulations, like checking if a given string is all in uppercase.

Step 1: Using the isupper() Method

The easiest way to check if a given string is all in uppercase is by using the built-in isupper() method. This method returns True if all the characters in the given string are uppercase, otherwise, it returns False.

Here’s an example:

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def is_uppercase(string):
    return string.isupper()
 
test_string1 = "HELLO16WORLD"
test_string2 = "Hello World"
 
print(is_uppercase(test_string1))  # Output: True
print(is_uppercase(test_string2))  # Output: False

Step 2: Using a Custom Function

You can also write a custom function to check if a string is all uppercase. In this approach, you loop through the characters of the string and check if each character is an uppercase character.

Here’s an example:

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def is_uppercase(string):
    for char in string:
        if char.isalpha() and not char.isupper():
            return False
    return True
 
test_string1 = "HELLO16WORLD"
test_string2 = "Hello World"
 
print(is_uppercase(test_string1))  # Output: True
print(is_uppercase(test_string2))  # Output: False

In this example, we use the isalpha() and isupper() methods to check if a character is an uppercase letter. If the character is an uppercase letter, we continue to check the next character. If a non-uppercase letter is found, the function returns False.

Full code:

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def is_uppercase(string):
    return string.isupper()
 
test_string1 = "HELLO16WORLD"
test_string2 = "Hello World"
 
print(is_uppercase(test_string1))
print(is_uppercase(test_string2))
 
def is_uppercase_custom(string):
    for char in string:
        if char.isalpha() and not char.isupper():
            return False
    return True
 
test_string1 = "HELLO16WORLD"
test_string2 = "Hello World"
 
print(is_uppercase_custom(test_string1))
print(is_uppercase_custom(test_string2))

Output:

True
False
True
False

Conclusion

In this tutorial, we discussed two different ways to check if a string is all uppercase in Python.

The first method using the built-in isupper() method is the most straightforward and recommended approach. The second approach, creating a custom function, can be used when you need more control over the process.

Both methods are valid and can help you easily determine if a given string is all uppercase.