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Regular Expressions Cookbook, 2nd Edition
book

Regular Expressions Cookbook, 2nd Edition

by Jan Goyvaerts, Steven Levithan
August 2012
Intermediate to advanced content levelIntermediate to advanced
609 pages
19h 16m
English
O'Reilly Media, Inc.
Content preview from Regular Expressions Cookbook, 2nd Edition

8.16. Matching IPv4 Addresses

Problem

You want to check whether a certain string represents a valid IPv4 address in 255.255.255.255 notation. Optionally, you want to convert this address into a 32-bit integer.

Solution

Regular expression

Simple regex to check for an IP address:

^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$
Regex options: None
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Accurate regex to check for an IP address, allowing leading zeros:

^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}↵
(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$
Regex options: None
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Accurate regex to check for an IP address, disallowing leading zeros:

^(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}↵
(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])$
Regex options: None
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Simple regex to extract IP addresses from longer text:

\b(?:[0-9]{1,3}\.){3}[0-9]{1,3}\b
Regex options: None
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Accurate regex to extract IP addresses from longer text, allowing leading zeros:

\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}↵
(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b
Regex options: None
Regex flavors: .NET, Java, JavaScript, PCRE, Perl, Python, Ruby

Accurate regex to extract IP addresses from longer text, dis25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9]allowing leading zeros:

\b(?:(?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\.){3}↵ (?:25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])\b ...
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Publisher Resources

ISBN: 9781449327453Supplemental ContentErrata Page