Learn How to Check if a String Is a Number in Python 3

In this tutorial, we will learn how to check if a string is a number in the Python 3 programming language.

Python 3 has a built-in string function called str.isnumeric() which will check whether a string is numeric or not. However, the str.isnumeric() function will return False for floating-point numbers. To check if a string is a float, we can use a try-except statement.

Python is string numeric

Python str.isnumeric() function will return True if the given string is numeric or return False otherwise.

Example 1

print(str.isnumeric("10"))

The Above python code will return True since “10” is a numeric value.

True

Example 2

print(str.isnumeric("abc"))

The Above python code will return False.

We can also use the isnumeric() function with a string variable as follows.

number = "100"
print(number.isnumeric())

To return True, the whole string has to be numbers only, or it will return False. For Example, the following code will return False since the variable number contains the letter “A”.

number = "100A"
print(number.isnumeric())

Check if a string is a Float in Python 3

Python str.isnumeric() function will return False for the floating-point numbers. But we can write a simple function using the try-except statement to check whether a string is a floating-point number or not.

def is_number(string):
    try:
        float(string)
        return True
    except ValueError:
        return False

As per the above python code, we created a new function called is_number(). The Function will simply try to convert the given string to a float. If the string can be converted to float, then the is_number function will return True.

Example

def is_number(string):
    try:
        float(string)
        return True
    except ValueError:
        return False
        
print(is_number("10.5"))

The Above Python Code will return True.

Summary

In this tutorial, we learned how to check if a string is a number in python programming.

We used the python str.isnumeric() function to check whether a string is numeric or not.
To check Floating point numbers, we wrote a simple python function called is_number().

e Learning