isupper()

my_str.isupper()

my_str='WELCOME TO PYTHON'
print(my_str.isupper())      # Output is True 

my_str='Welcome to Python'
print(my_str.isupper())      # Output is False

my_str='Welcome To Python'
print(my_str.isupper())      # Output is False

my_str='WELCOME 100'
print(my_str.isupper())      # Output is True

Handling Mixed Characters

isupper() returns True even if the string contains numbers or special characters, as long as all alphabetic characters are uppercase:

my_str = 'HELLO123!@'
print(my_str.isupper())  # Output: True

Use Case: Validating Form Input

In form submissions, you might require the input to be in uppercase. isupper() helps validate that:

user_input = "PASSWORD"
if user_input.isupper():
    print("Valid input.")

Checking Empty Strings

isupper() returns False for empty strings because there are no characters to check:

empty_str = ''
print(empty_str.isupper())  # Output: False

Use Case: Cleaning Up Data

In data processing, you might want to filter out strings that aren't uppercase:

data = ["HELLO", "World", "PYTHON", "code"]
upper_data = [word for word in data if word.isupper()]
print(upper_data)  # Output: ['HELLO', 'PYTHON']

Mixed Case Strings

Strings with mixed cases will return False:

print("HelloWorld".isupper())  # Output: False

Checking Strings with Spaces

isupper() ignores spaces, and checks only alphabetic characters:

text = 'HELLO WORLD'
print(text.isupper())  # Output: True

Handling Unicode Characters

Unicode characters are also checked, and the method still works for non-ASCII characters:

text = 'PYTHON 你好'
print(text.isupper())  # Output: True

Combining with Other String Methods

Use isupper() with other string methods for flexible validation:

text = 'password'
print(text.upper().isupper())  # Output: True

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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