python-regexHow to match an IP address with regex in Python?

Regex (Regular Expression) is a powerful tool for matching patterns in strings. In Python, it can be used to match an IP address with the re module.

Example code

import re

# Sample IP address
ip = "10.10.10.1"

# Regex for IP address
regex = '''
^ # Start of the line
(25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?) # First number (0-255)
\. # Dot
(25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?) # Second number (0-255)
\. # Dot
(25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?) # Third number (0-255)
\. # Dot
(25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?) # Fourth number (0-255)
$ # End of the line
'''

# Compile the Regex
pattern = re.compile(regex)

# Match the IP address
match = pattern.match(ip)

# Print the match
print(match)

Output example

<re.Match object; span=(0, 11), match='10.10.10.1'>

The code above uses the re module to compile a regex pattern for matching an IP address. The regex pattern consists of four parts, each representing a number from 0 to 255. The pattern is then used to match the IP address, and the result is printed.

Code explanation

1. ^: Start of the line
2. (25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?): First number (0-255)
3. \.: Dot
4. (25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?): Second number (0-255)
5. \.: Dot
6. (25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?): Third number (0-255)
7. \.: Dot
8. (25[0-5]|2[0-4][0-9]|[0-1]?[0-9][0-9]?): Fourth number (0-255)
9. $: End of the line

Helpful links

• Python Regular Expressions
• Regular Expression Tutorial

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