Python has many helper functions in its libraries that always help us with some day to day tasks. Let`s see how the string islower () method works which actually checks if all characters in the string are lowercase.

Syntax: string .islower ()

Parameters: None

Returns: True if all the letters in the string are in lower case and False if even one of them is in upper case.

Code # 1: Demonstration of islower ()

# Python3 demo code # islower () working   # initialization string islow_str = " pythonengineering " not_islow = "Geeksforgeeks"   # check which line # completely below print ( "Is pythonengineering full lower? : " + str (islow_str.islower ())) print ( "Is Geeksforgeeks full lower?: " + str (not_islow.islower ()))

Exit:

 Is pythonengineering full lower?: True Is Geeksforgeeks full lower?: False 

Practical use: This function can be used in many ways and has many practical uses. such applications are lowercase validation, proper name validation, sentence validation, which requires all lowercase letters. Below is a small example demonstrating the use of the islower () method.

Code # 2: Practical Demonstration islower () method

# Python3 demo code # using the islower () method   # check proper names. # capitalized nouns   test_str = " Geeksforgeeks is most rated Computer Science portal and is highly recommended "    # line splitting list_str = test_str.split ()   count = 0   # counting lowercase for i in list_str: if (i.islower ()):   count = count + 1   # print proper nouns print ( "Number of proper nouns in this sentence is:" + str ( len (list_str) - count))

Output:

 Number of proper nouns in this sentence is: 3