How to Check if given String contains only Alphanumeric Characters in Python?

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Python String – Check if Alphanumeric – isalnum()

To check if given string contains only alphanumeric characters in Python, use String.isalnum() function.

The function returns True if the string contains only alphanumeric characters and False if not.

Following are the allowed Alphanumeric Characters.

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789

In this example, we take a String with only alphanumeric characters. We will apply isalnum() function.

Python Program

str = 'pythonexamples125'

isalnum = str.isalnum()

print('Is String Alphanumeric :', isalnum)

Output

Is String Alphanumeric : True

The function returns boolean value True, since the string contains only alphabets and numbers.

In this example, we take a String with only alphanumeric characters and spaces. We will apply isalnum() function.

Python Program

str = 'Python Examples 125'

isalnum = str.isalnum()

print('Is String Alphanumeric :', isalnum)

Output

Is String Alphanumeric : False

The function returns the boolean value False since the string contains spaces which are not alphanumeric.

In this example, we take a String with only alphanumeric characters and special characters. We will apply isalnum() function to the String.

Python Program

str = "Python Examples $125 @6 O'Clock"

isalnum = str.isalnum()

print('Is String Alphanumeric :', isalnum)

Output

Is String Alphanumeric : False

The function returns the boolean value False since the string contains special characters which are not alphanumeric.

In summary, to determine if a given string is alphanumeric, use String.isalnum() function.