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Python String islower() Method

Check how the Python islower() method determines if all alphabetic characters in a string are lowercase, handling edge cases like empty strings, numbers, and mixed cases.

The String islower() method returns True if the string is not empty and all the alphabet characters are lowercase. Otherwise, it returns False.

Syntax

my_string.islower()

islower() Parameters

Python String islower() method does not take any parameters.

islower() Return Value

Python String islower() method returns:

  • True if all characters in the string are lowercase.
  • False if the string does not contain at least one cased character or if the string contains at least one uppercase alphabetic character.

Examples

Example 1: Check if all characters in the string are lowercase

The islower() method returns True if all characters in the string are lowercase.

my_str = 'abcd'
result = my_str.islower()
print(result) # Output: True

output

True

The method returns False, if the string does not contain at least one cased character.

my_str1 = '123$@%'
my_str2 = 'a123$@%'

print(my_str1.islower()) # Output: False
print(my_str2.islower()) # Output: True

output

False
True

The method also returns False, if the string contains at least one uppercase alphabet.

my_str = '123A$@%'

print(my_str.islower()) # Output: False

output

False

Example 2: Check if an Empty String is lowercase

An empty string is not lowercase.

my_str = ''

print(my_str.islower()) # Output: False

output

False
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