isnumeric() in Python

Python has a built-in method called isnumeric() that can be used to check whether a given string contains only numeric characters. In this article, we will look at how it works and provide some examples to show how it can be used in practice.

Syntax

The syntax for the isnumeric() method is as follows:

string.isnumeric()

Here, string is the string that we want to test for numeric characters. The method returns True if all the characters in the string are numeric, and False otherwise.

Examples

Let's start with some simple examples of how to use isnumeric():

s1 = '1234'
s2 = '1.23'
s3 = '1a2b3c4d'
s4 = '१२३४'
s5 = '①②③④'

print(s1.isnumeric())  # True
print(s2.isnumeric())  # False
print(s3.isnumeric())  # False
print(s4.isnumeric())  # True
print(s5.isnumeric())  # True

As we can see from the output, isnumeric() correctly identifies which strings contain only numeric characters.

Note that isnumeric() does not handle negative numbers or decimal points. In order to check for negative numbers, we can use the - (minus) character along with isnumeric(). For example:

s6 = '-1234'
print(s6[0] == '-' and s6[1:].isnumeric())  # True

To check for decimal points, we can use a regular expression. For example:

import re

s7 = '12.34'
print(re.match(r'^\d+(\.\d+)?$', s7) is not None)  # True

Conclusion

In conclusion, isnumeric() is a handy method in Python for checking whether a given string contains only numeric characters. It is simple to use and can save us a lot of time when working with strings in our programs.