Python – Check If String Contains Only Letters and Numbers

In this tutorial, we will look at how to check if a string contains only letters and numbers in Python with the help of examples.

How to check if a string contains only letters and numbers?

You can use the string isalnum() function to check if a string contains only letters (that is, alphabets) and/or numbers in Python. The following is the syntax –

# check if string s contains only alphanumeric characters
s.isalnum()

It returns True if all the characters in the string are alphanumeric (containing only alphabets and/or numbers). If any of the characters is not alphanumeric, it returns False.

Let’s look at an example.

# create a string
s = "Bunny123"
# check if string contains only alphanumeric characters
print(s.isalnum())

Output:

True

We get True as the output. This is because all the characters in the string s above are either letters or numbers.

Let’s look at another example.

# create a string
s = "Bunny_123"
# check if string contains only alphanumeric characters
print(s.isalnum())

Output:

False

Here, we get False as the output. This is because not all characters in the string s above are alphanumeric. One of the characters in the string, “_” is neither an alphabet nor a digit.

For more on the string isalnum() function, refer to its documentation.

You might also be interested in –

• Python – Check If String Contains Only Letters
• Python – Check if String Contains Only Numbers
• Check If String Contains Only Certain Characters in Python