Question

so basically I want to detect if in these strings:

Hello 123 My 222 dear 112 troll 12 8889

192.1.1.254:10000

the numbers are in a format like this:
[0 to 255][ANYTHING][0 to 255][ANYTHING][0 to 255][ANYTHING][0 to 255][ANYTHING][0 to 65536]

Does anyone know how I can build such a regex?

It is for detecting if anyone posts an IP:Port in unusual format to bypass default ip:port filters.

Edit: As for the first comment: I do not know regex and what I have tried is:

if(regex_match("192.168 najlepszy serwer SAMP!!1 1 join1!! 8080","/^[0-2](*)?[0-5](*)?[0-5](*).(*)[0-2](*)?[0-5](*)?[0-5](*).(*)[0-2](*)?[0-5](*)?[0-5](*).(*)[0-2](*)?[0-5](*)?[0-5](*)?$/"))
{
    print("Cannot send message");
}
else
{
    print("New message for everyone! :)");
}

and some other not working regexes.

Answer 1

I’d suggest you read up on Regex syntax. For starters . is special and matches any character. Also doing something like [0-2][0-5][0-5] won’t catch something like 192 as 9 is not within 0-5.

According to your requirements here’s a Regex that should roughly do what you want

([0-2]?\d{1,2}).*([0-2]?\d{1,2}).*([0-2]?\d{1,2}).*([0-2]?\d{1,2}).*(\d{1,5})?

Each of the ([0-2]?\d{1,2}) portions will match 1 or 2 digits preceded optionally with a 0,1, or 2. Each () will capture a group which you can then examine using a Regex engine. You will need to examine this group as the Regex for each of those portions will match numbers above 255 (specifically 256-299).

The last group (\d{1,5})? is to catch the port number, again you will have to examine this as it will catch any 1 to 5 digit number (hence the {1,5}). The ? makes the group optional, remove it if you want it to have to match against a port number.

As far as doing Regex in C, I haven’t had much experience but there should be a way to get all the grouped matches and inspect them. Unfortunately they will be strings so you will have to convert them to integers to examine them.