How can I check if a string contains only alphanumeric characters in Python?
Benjamin C

To check if a string contains only alphanumeric characters in Python, you can use theisalnum() string method or a regular expression pattern to validate the string's format. 1. Usingisalnum(): Theisalnum() method checks if all characters in a string are alphanumeric (i.e., letters or digits). It returnsTrue if the string contains only alphanumeric characters andFalse otherwise. Here's an example of how you can perform this check usingisalnum():

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def is_alphanumeric(string):
    return string.isalnum()

# Usage:
input_string = input("Enter a string: ")
if is_alphanumeric(input_string):
    print("The string contains only alphanumeric characters.")
else:
    print("The string contains non-alphanumeric characters.")

In the above code, theis_alphanumeric() function takes astring parameter to check. It uses theisalnum() method of the string object to determine if the string contains only alphanumeric characters. The function returns the result of this check. You can use theis_alphanumeric() function by providing a string as an argument. It will check if the string contains only alphanumeric characters using theisalnum() method. The result is then printed accordingly. 2. Using regular expressions: Regular expressions provide a powerful way to match and validate string patterns. You can use there module to define a regular expression pattern that matches only alphanumeric characters and apply it to the string using thematch() function. Here's an example of how you can perform this check using regular expressions:

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import re

def is_alphanumeric(string):
    pattern = r'^[a-zA-Z0-9]+$'
    return re.match(pattern, string) is not None

# Usage:
input_string = input("Enter a string: ")
if is_alphanumeric(input_string):
    print("The string contains only alphanumeric characters.")
else:
    print("The string contains non-alphanumeric characters.")

In the above code, theis_alphanumeric() function takes astring parameter to check. It defines the regular expression patternr'^[a-zA-Z0-9]+$', which matches a string that consists of one or more alphanumeric characters. The function applies the pattern to the input string using there.match() function and checks if there is a match. You can use theis_alphanumeric() function by providing a string as an argument. It will check if the string contains only alphanumeric characters based on the regular expression pattern. The result is then printed accordingly. Both approaches allow you to determine if a string contains only alphanumeric characters. Choose the approach that suits your requirements and coding style.

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