Python String isalnum() Method (original) (raw)

Last Updated : 21 Apr, 2025

The **isalnum() method is a string function in Python that checks if all characters in the given string are alphanumeric. If every character is either a letter or a number, isalnum() returns **True. Otherwise, it returns **False.

**For Example:

Python `

s = "Python123" res = s.isalnum() print(res)

`

**Explanation: In this example, **s contains only letters and numbers, so **isalnum() returns **True.

Syntax

s.isalnum()

**Parameters:

• This method does not accept any parameters.

**Return Type:

• Returns **True if all characters in the string are alphanumeric.
• Returns **False if there are any non-alphanumeric characters.

Examples of isalnum() Method

Example 1: Empty String

An empty string will return **False since there are no alphanumeric characters.

Python `

s = "" res = s.isalnum() print(res)

`

Example 2: String with Only Digits

The method will also return **True for a string with only numeric characters.

Python `

s = "123456" res = s.isalnum() print(res)

`

Example 3: String with Only Letters

Similarly, a string containing only letters will return **True.

Python `

s = "Python" res = s.isalnum() print(res)

`

Example 4: String with Non-Alphanumeric Characters

If the string contains a space and an exclamation mark, so **isalnum() returns **False.

Python `

s = "Python 123!" res = s.isalnum() print(res)

`

**Explanation: in this code, **isalnum() returns **False because the string **s contains **space ” “ and **exclamation mark (!) which are neither numbers nor alphabets.