Python String isalnum() Method

The Python String isalnum() Method tests whether or not all characters are alphanumeric. A letter(a-z) or a number(0-9) character is classified as alphanumeric. Special chars, like spaces, are not permitted.

The syntax of the method is: str.isalnum()

Key Points:

• Return Type: Boolean i.e. True or False
• Parametric Values: There are no isalpha() function parameters.
• There should be no spaces in the string.
• False returns the null string as well.
• Not case responsive, i.e., value return does not depend on string subject.

Return Value from isalnum()

The isalnum() returns:

• If all characters are alphanumeric, the isalnum() method returns True, which implies alphabet letter (a-z and number (0-9).
• If the string is empty, isalnum() returns False.

Below is the python program to demonstrate the isalnum() function:

str = "TheBestLearningResourceforOnlineEducation"; 
print (str.isalnum())
str = "The Best Learning Resource for Online Education";
print (str.isalnum())

When we run above the program, the outcome is as follows:

True
False

Working of isalnum()

username = input("Choose a username:")
if username.isalnum() == True:
print("Your new username is ", username)
else:
print("This username is invalid.")

When we run above the program, the outcome is as follows:

Choose a username:DThakur
Your new username is DThakur

Below are several other functions that we can use to work with string in Python 3