IPv4 Address in PY
Match valid IPv4 addresses with each octet constrained to 0–255.
Try it in the PY tester →Pattern
regexPY
(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?) (flags: g)Python (re) code
pyPython
import re
pattern = re.compile(r"(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?)")
input_text = "192.168.1.1"
for m in pattern.finditer(input_text):
print(m.group(0))Stdlib `re` module — no third-party dependency. Works on Python 3.6+.
How the pattern works
Each octet alternation covers 250-255, 200-249, and 0-199 ranges to ensure strict 0-255 validity. Three octets with dots are matched, then the final octet.
Examples
Input
192.168.1.1Matches
192.168.1.1
Input
255.255.255.0Matches
255.255.255.0
Input
999.999.999.999No match
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