Python 3 reference · String Methods

Python String islower() Method

Return True if all cased characters are lower case and there is at least one cased character.

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Syntax

str.islower()

True or False.

Basic useTry it yourself

print("hello".islower(), "hello 123".islower(), "Hello".islower(), "123".islower())

Output

True True False False

Filter lower-case wordsTry it yourself

words = ["python", "Java", "go"]
print([w for w in words if w.islower()])

Output

['python', 'go']

Version	Change
Python 3.0	Added

str.isupper() · Return True if all cased characters are upper case and there is at least one cased character.
str.lower() · Return a copy of the string with all cased characters converted to lower case.
str.istitle() · Return True if the string is title-cased: each word starts with an upper-case letter followed by lower-case letters.
Python Strings · tutorial