convertion of hexadecimal into ipaddress in c#

Question

I need a logic how to convert hexadecimal to IP(IPV4) address for example

6F6F6F6F(HEXADECIMAL) - 111.111.111.111(IPADDRESS)
FFFFFFFF(HEXADECIMAL) - 255.255.255.255(IPADDRESS)

Answer 1

You can try using Linq to query the original string. The query can be

1. Split original string into chunks of size 2
2. Convert each chunk into int value
3. Join all these int's into the final string

using System.Linq;

...

string source = "6F6F6F6F";

string address = string.Join(".", source
  .Chunk(2)
  .Select(chunk => Convert.ToInt32(new string(chunk), 16)));

Demo:

using System.Linq;

...

static string MyConvert(string source) => string.Join(".", source
  .Chunk(2)
  .Select(chunk => Convert.ToInt32(new string(chunk), 16)));

string[] tests = {
  "6F6F6F6F",
  "FFFFFFFF",
};

string result = string.Join(Environment.NewLine, tests
  .Select(test => $"{test}(HEXADECIMAL) - {MyConvert(test)}(IPADDRESS)"));

Console.Write(result);

Outcome:

6F6F6F6F(HEXADECIMAL) - 111.111.111.111(IPADDRESS)
FFFFFFFF(HEXADECIMAL) - 255.255.255.255(IPADDRESS)

Edit: Reverse can be Linq based as well:

1. We split the source by .
2. Parse each item to int and format as hexadecimal with 2 mandatory digits
3. Concat all these chunks into the result string

string source = "123.45.67.221";

string result = string.Concat(source
  .Split('.')
  .Select(item => int.Parse(item).ToString("X2")));

Edit 2: You can use GroupBy instead of Chunk in case of old .net versions:

string address = string.Join(".", source
  .Select((item, index) => new { item = item, group = index / 2 })
  .GroupBy(pair => pair.group, pair => pair.item)
  .Select(group => Convert.ToInt32(new string(group.ToArray()), 16)));

Fiddle