Extracting IP Address From a Given String Using Regular Expressions

Last Updated : 20 Sep, 2023
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Prerequisites: 

Given a string str, the task is to extract all the  IP addresses from the given string. Let us see how to extract IP addresses from a file.

Input: 

str="The IPV4 address of Port A is: 257.120.223.13. And the IPV6 address is:fffe:3465:efab:23fe:2235:6565:aaab:0001"

Output:

257.120.223.13
fffe:3465:efab:23fe:2235:6565:aaab:0001

Create a regex pattern to validate the number as written below:

  1. Regex_IPV4 = “(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])“
  2. Regex_IPV6="((([0-9a-fA-F]){1,4})\\:){7}([0-9a-fA-F]){1,4}"

Follow the below steps to implement the idea:

  • Create a regex expression to extract all the IP Addresses from the string.
  • Use Pattern class to compile the regex formed.
  • Use the matcher function to find.

Below is the implementation of the above approach:

C++ 
// C++ Program to Extract IP
// From given string
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // String to observe
    string subject
        = "The IPV4 address of Port A is :257.120.223.13 . "
          "And the IPV6 address "
          "is:fffe:3465:efab:23fe:2235:6565:aaab:0001";

    // Regex for IPV4
    regex pattern(
        "(\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3})");

    cout << "Available IP Addresses in the Given String Are:"
         << endl;

    // Iterating over string to extract all
    // IPV4 patterns
    for (regex_iterator<string::iterator> it(
             subject.begin(), subject.end(), pattern);
         it != regex_iterator<string::iterator>(); ++it) {
        cout << it->str() << endl;
    }

    // Regex for IPV6
    regex pattern1(
        "((([0-9a-fA-F]){1,4})\\:){7}([0-9a-fA-F]){1,4}");

    // Iterating over string to extract all
    // IPV6 patterns
    for (regex_iterator<string::iterator> it(
             subject.begin(), subject.end(), pattern1);
         it != regex_iterator<string::iterator>(); ++it) {
        cout << it->str() << endl;
    }

    return 0;
}
Java 
// Java Program to Extract IP
// From given string
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class GFG {

    // Driver Code
    public static void main(String[] args)
    {

        // String containing in it
        String str
            = " The IPV4 address of Port A is :257.120.223.13 . And the IPV6 address is:fffe:3465:efab:23fe:2235:6565:aaab:0001";
        System.out.println(
            "Available IP Addresses in the Given String Are:");
        extractIP_Addresses(str);
    }

    // Function to extract IP Address
    // from a given string
    static void extractIP_Addresses(String str)
    {

        // You can Add n number of Email
        // formats in the below given
        // String Array.
        String strPattern[] = {
            "(\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3})",
            "((([0-9a-fA-F]){1,4})\\:){7}([0-9a-fA-F]){1,4}"
        };

        // Extracting all Patterns from the string
        for (int i = 0; i < strPattern.length; i++) {
            Pattern pattern
                = Pattern.compile(strPattern[i]);
            Matcher matcher = pattern.matcher(str);
            while (matcher.find()) {
                System.out.println(matcher.group());
            }
        }
    }
}
Python3 
import re

# String to observe
subject = ("The IPV4 address of Port A is :257.120.223.13 . "
           "And the IPV6 address "
           "is:fffe:3465:efab:23fe:2235:6565:aaab:0001")

# Regex for IPV4
pattern_ipv4 = r'\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b'

print("Available IP Addresses in the Given String Are:")

# Find all IPV4 patterns
ipv4_addresses = re.findall(pattern_ipv4, subject)
for address in ipv4_addresses:
    print(address)

# Regex for IPV6
pattern_ipv6 = r'\b(?:[A-Fa-f0-9]{1,4}:){7}[A-Fa-f0-9]{1,4}\b'

# Find all IPV6 patterns
ipv6_addresses = re.findall(pattern_ipv6, subject)
for address in ipv6_addresses:
    print(address)
C# 
using System;
using System.Text.RegularExpressions;

namespace GFG
{
  class Program
  {
    static void Main(string[] args)
    {
      // String containing IP addresses
      string str = " The IPV4 address of Port A is :257.120.223.13 . And the IPV6 address is:fffe:3465:efab:23fe:2235:6565:aaab:0001";
      Console.WriteLine("Available IP Addresses in the Given String Are:");
      ExtractIPAddresses(str);
    }

    static void ExtractIPAddresses(string str)
    {
      // Patterns for IPV4 and IPV6 addresses
      string[] strPattern = {
        @"(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})",
        @"(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})\:(([0-9a-fA-F]){1,4})"
        };

      // Extracting all patterns from the string
      for (int i = 0; i < strPattern.Length; i++)
      {
        Regex pattern = new Regex(strPattern[i]);
        MatchCollection matches = pattern.Matches(str);

        foreach (Match match in matches)
        {
          Console.WriteLine(match.Value);
        }
      }
    }
  }
}
JavaScript 
// String to observe
const subject = "The IPV4 address of Port A is :257.120.223.13 . And the IPV6 address is:fffe:3465:efab:23fe:2235:6565:aaab:0001";

// Regex for IPV4
const pattern = /(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/g;

console.log("Available IP Addresses in the Given String Are:");

// Iterating over string to extract all IPV4 patterns
let match;
while ((match = pattern.exec(subject)) !== null) {
  console.log(match[0]);
}

// Regex for IPV6
const pattern1 = /((([0-9a-fA-F]){1,4})\:){7}([0-9a-fA-F]){1,4}/g;

// Iterating over string to extract all IPV6 patterns
while ((match = pattern1.exec(subject)) !== null) {
  console.log(match[0]);
}

Output
Available IP Addresses in the Given String Are:
257.120.223.13
fffe:3465:efab:23fe:2235:6565:aaab:0001

Time Complexity: O(n) 
Space Complexity: O(1)


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