Regular expression - regex - matching

Question

How do I make an expression to match this below: (including spaces , whitespaces, other characters in the numbers)? Example:

asdasd (S)FS-980/24/BS/02 , asdasd

ffff (S)FS-9525/23/BS/12ss, IP000003587

FSW-952/24/BSB/02

FS-2/24/F/02

FS-4444/23/F/11

I mean if invoice number : FS -444 4/23/F/11 - it also correct to: FS-4444/23/F/11, or FS-4444g/23g/F/1g1

i try like this: ...FS(W)-../.{2}/..(.)/\s.{2}

Demo: https://regex101.com/r/bq7lIM/3

Answer 1

You could update your pattern to get the matches first. Then do a replacement over those matches, and remove the characters that you don't want.

To match the strings:

(?:\([A-Z]+\))?FS[A-Z ]*-\d(?:[^\n,()-]*\w)?

The pattern matches:

• (?:\([A-Z]+\))? Optionally match ( followed by 1+ chars A-Z and then )
• FS[A-Z ]*- match FS followed by optional chars A-Z or spaces
• \d Match a digit
• (?:[^\n,()-]*\w)? Optionally match any char except what is listed in the character class, and end on a word character

If you want to match a space without a newline in C# you can also use \p{Zs}

Regex demo

To replace the unwanted characters over the matched parts:

(?<=^FS-[a-zA-Z0-9]*)[a-z]|[\p{Zs}\ta-z](?=[a-zA-Z0-9\p{Zs}\t]*$)

This pattern will match all lowercase characters at the beginning of the string before the - and match all lowercase chars a-z or spaces at the end of the string, not crossing any characters other then what is listed in the character class present in the positive lookahead assertion.

See a Regex demo and a C# demo.

string patternMatch = @"(?:\([A-Z]+\))?FS[A-Z ]*-\d(?:[^\n,()-]*\w)?";
string patternReplace = @"(?<=^FS-[a-zA-Z0-9]*)[a-z]|[\p{Zs}\ta-z](?=[a-zA-Z0-9\p{Zs}\t]*$)";
string input = @"Fakturasadas : (S)FSK-69/23/GFK/12hjkhjkddddd
(S)FSK-69/23/GFK/ 1 2 
(S)FSK-69/23/GFK/12";

var strings = Regex
    .Matches(input, patternMatch)
    .Cast<Match>().Select(match => {                    
        return Regex.Replace(
            match.Value,
            patternReplace,
            ""
        );
    }
);

foreach (var s in strings) {
    Console.WriteLine(s);
}

Output

(S)FSK-69/23/GFK/12
(S)FSK-69/23/GFK/12
(S)FSK-69/23/GFK/12