Python String islower() Method

2022-11-06T19:13:33.618Z

The str.islower() method returns True if all the characters in a string are in lowercase. If it finds at least one of the characters in uppercase, it returns False.

Example:

text ="python is awesome"
print(text.islower())

Output

True

Syntax

The Syntax of the str.islower() function is:

str.islower()

Here, str is a string.

Parameters

The str.islower() function does not take any parameters.

Return Value

The str.islower() function returns:

True if all the characters in the string are in lowercase
False if at least one of the characters in the string is in uppercase

Example 1: Python Program to check if the string is in lowercase

The lower() method returns:

True: If all the characters in the string is lowercase
True: If the string has a combination of numbers and lowercase characters
True: If the string has a combination of numbers, special case, and lowercase characters
False: If the string has one or more uppercase character
False: If the string has only whitespace or numbers


# lowercase string
text ="python"
print(text.islower())

# string with numbers
text ="python3 is released in the year 2008"
print(text.islower())

# string with special chars
text ="https://www.python.org"
print(text.islower())

# titlecase string
text ="Python"
print(text.islower())

# Uppercase string
text ="PYTHON"
print(text.islower())

# Mixed Case string
text ="Welcome To Python Tutorial"
print(text.islower())

# String with only numbers
text ="2022"
print(text.islower())

Output

True
True
True
False
False
False
False

Example 2: How to use islower() function in a Program?

In the real-world use case, we can use islower() method to check if the given string consists of only lowercase characters. Here are a few examples where lowercase strings are preferred:

Checking Email Address
Verifying username
Domain Names

# Method to verify if the text is lower
def check_lower(text):
    if text.islower() == True:
        return "All the characters in the sentence are in lowercase"
    else:
        return "one or more characters in the sentence are not in lowercase"

# All characters are in lowercase
print(check_lower("there are seven continents in the world."))

# some characters are in uppercase
print(check_lower("There are Seven Continents in the World."))

Output

All the characters in the sentence are in lowercase
one or more characters in the sentence are not in lowercase

Reference: Python Official String Methods