How can I use Python to check if a string is a number?

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#1

How can I use Python to check if a string is a number (float or int)?

I want to check if a string represents a numeric value (either an integer or a float) in Python. For example:

def is_number(s): try: float(s) return True except ValueError: return False The above code works but feels a bit clunky. How can I achieve this more effectively using python check if string is number?

#2

Hey @keerti_gautam

_“Using str.replace with float()” You can clean the string to handle edge cases like signs (+, -) and decimals before checking if it can be converted to a float.

def is_number(s):
    if s.replace('.', '', 1).replace('-', '', 1).isdigit():
        return True
    try:
        float(s)
        return True
    except ValueError:
        return False

print(is_number("123"))     # True
print(is_number("12.3"))    # True
print(is_number("abc"))     # False
#3

Hey Everyone!

Hope All are doing great! Here is the Answer to the above Question:-

“Using Regular Expressions” Regular expressions provide a more compact and precise way to validate if a string is a numeric value. This method is cleaner and ensures that you only allow valid number formats, including optional signs and decimals.

import re

def is_number(s):
    return bool(re.match(r'^-?\d+(\.\d+)?

Regular expressions are great for advanced string validation, especially when you want to handle optional signs and decimals in one go., s))

print(is_number(“123”)) # True print(is_number(“12.3”)) # True print(is_number(“-12.3”)) # True print(is_number(“abc”)) # False


Regular expressions are great for advanced string validation, especially when you want to handle optional signs and decimals in one go.
#4

“Using str.isdigit for Integers or Try-Catch for Floats” To simplify the logic, you can split the validation into separate checks for integers and floats. This method keeps it easy to understand and manage.

def is_number(s):
    if s.isdigit():  # Checks for integers
        return True
    try:
        float(s)  # Floats are checked here
        return True
    except ValueError:
        return False

print(is_number("123"))     # True
print(is_number("12.3"))    # True
print(is_number("abc"))     # False

This approach is effective for basic cases, where you first check if the string is an integer (using isdigit), and then handle floats using the try-except block.

Let me know if you have further doubts on the above question.