Regex Cheatsheet - Regular Expression Quick Reference
Quick reference for regular expression patterns. Character classes, quantifiers, anchors, and common patterns.
IPv4 Address Pattern
Common PatternMatch IPv4 address (0.0.0.0 - 255.255.255.255)
Pattern
^((25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(25[0-5]|2[0-4]\d|[01]?\d\d?)$Syntax
Explanation
Strictly validates each octet between 0-255.
Examples
192.168.1.1LAN IP
Matches: 192.168.1.1
255.255.255.0Subnet mask
Matches: 255.255.255.0
127.0.0.1Localhost IP
Matches: 127.0.0.1
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