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.