python-regexHow to validate an IP using Python regex?

Python regex can be used to validate an IP address. The following example code block uses regex to validate an IP address:

import re

def validate_ip(ip):
    regex = '''^(25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)\.(
            25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)\.(
            25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)\.(
            25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)'''
    if(re.search(regex, ip)):
        print("Valid IP")
    else:
        print("Invalid IP")

ip = "192.168.1.1"
validate_ip(ip)

The output of the example code is:

Valid IP

Code explanation

1. import re: This imports the re module which provides regular expression matching operations.
2. regex = '''^(25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)\.( 25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)\.( 25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)\.( 25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?)''': This defines the regex pattern which is used to validate the IP address.
3. if(re.search(regex, ip)):: This uses the re.search() method to search for the regex pattern in the given IP address.
4. print("Valid IP"): This prints the output if the IP address is valid.
5. print("Invalid IP"): This prints the output if the IP address is invalid.

Helpful links

• Python Regular Expression
• Python re Module

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