How To Check For Digits In A String In Python

In Python, checking if a given string contains any digits can be a common requirement for various applications like password validation, extracting numerical values from text, and a lot more. In this tutorial, we will explore different methods to check for digits in a string in Python programming language.

Step 1: Using Python’s isdigit() function

Python’s in-built string method isdigit() can be used to check if a string contains only digits or not. This function returns True if all the characters in the string are digits, and False otherwise.

Here is an example:

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def check_digits_in_string(input_string):
    for character in input_string:
        if character.isdigit():
            return True
    return False
 
string_with_digits = "abc12def3"
string_without_digits = "abcdef"
 
print(check_digits_in_string(string_with_digits)) # True
print(check_digits_in_string(string_without_digits)) # False

Output:

True
False

Step 2: Using Regular Expressions

Another method to check for digits in a string is by using Python’s re (Regular Expression) module. Below is an example of using regular expressions to search for digits in a string.

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import re
 
def check_digits_in_string(input_string):
    if re.search(r'\d', input_string):
        return True
    else:
        return False
 
string_with_digits = "abc12def3"
string_without_digits = "abcdef"
 
print(check_digits_in_string(string_with_digits)) # True
print(check_digits_in_string(string_without_digits)) # False

Output:

True
False

Step 3: Using List Comprehension and isdigit() function

You can also use a list comprehension with Python’s isdigit() function to check for digits in a string. Here’s an example:

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def check_digits_in_string(input_string):
    return any(character.isdigit() for character in input_string)
 
string_with_digits = "abc12def3"
string_without_digits = "abcdef"
 
print(check_digits_in_string(string_with_digits)) # True
print(check_digits_in_string(string_without_digits)) # False

Output:

True
False

Conclusion

In this tutorial, we learned three different methods to check for digits in a string in Python: using the isdigit() function, using regular expressions with the re module, and using list comprehension with the isdigit() function. Choose the method that best fits your needs. These methods are easy to implement and can be easily incorporated into your Python projects.