Python String isalnum()

Summary: in this tutorial, you’ll learn how to use the Python string isalnum() method to check if all characters in the string are alphanumeric.

Introduction to the Python string isalnum() method #

The string isalnum() method returns True if:

• all characters in the string are alphanumeric
• and the string has at least one character.

Otherwise, it returns False.

The following shows the syntax of the isalnum() method:

str.isalnum()Code language: CSS (css)

Functionally, the string str contains only alphanumeric characters if one of the following methods returns True:

• str.isalpha()
• str.isnumeric()
• str.isdecimal()
• str.isalpha()

Python string isalnum() examples #

The following example uses the isalnum() method to check if the string 'Python3' contains only alphanumeric characters:

version = 'Python3'
result = version.isalnum()

print(result)Code language: PHP (php)

Output:

TrueCode language: PHP (php)

It returns True because the string 'Python3' contains only letters and numbers.

The following example returns False because the string 'Python 3' contains a whitespace:

version = 'Python 3'
result = version.isalnum()

print(result)Code language: PHP (php)

Output:

FalseCode language: PHP (php)

Summary #

• Use the Python string isalnum() method to determine if all characters in the string are alphanumeric.