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.

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