Extracting IP Address From a Given String Using Regular Expressions

Prerequisites: 

• Regular Expressions
• IP address

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:

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)