How can I split a string into non-constants of the Regex (C#)

Question

I'm coding an Edifact Reader. An Edifact file consists of string lines like this:

string row = @"ABC+1+E522017332:101111757+MAX:MUSTERMANN:16890224+9'";

There is a set of rules that describe a valid line like this. The RegEX translation of this rules in this particular case looks like this:

Regex regex = new Regex(@"ABC\+\d{1}([A-Z0-9])?(\:\d{1})?\+[A-Z0-9]{1,12}\:[A-Z0-9]{9}\+[A-Z0-9]{0,45}\:[A-Z0-9]{0,45}\:\d{8}\+\d{1}(\d{4})?(\d{1})?([A-Z0-9]{1,7})?([A-Z0-9]{3})?([A-Z0-9]{15})?\'");

And it works just fine. But I also want to split this string respectively the non-constants in the RegEx. The result should look like this:

ABC 
1
null
null
E522017332
101111757
MAX
MUSTERMANN
16890224
9
null
null
null
null
null

How can I do it?

Answer 1

You only have the use the capture groups (...) for all the pieces you need:

Regex regex = new Regex(@"^(ABC)\+(\d{1})([A-Z0-9])?(\:\d{1})?\+([A-Z0-9]{1,12})\:([A-Z0-9]{9})\+([A-Z0-9]{0,45})\:([A-Z0-9]{0,45})\:(\d{8})\+(\d{1})(\d{4})?(\d{1})?([A-Z0-9]{1,7})?([A-Z0-9]{3})?([A-Z0-9]{15})?\'$");

string row = @"ABC+1+E522017332:101111757+MAX:MUSTERMANN:16890224+9'";

var match = regex.Match(row);

if (match.Success)
{
    for (int i = 1; i < match.Groups.Count; i++)
    {
        string value = match.Groups[i].Value;
        if (value == string.Empty)
        {
            value = "(null)";
        }
        Console.WriteLine(value);
    }
}

Now the Groups are numbered 1...many. But it is quite unreadable... You could give explicit names:

Regex regex = new Regex(@"^(?<abc>ABC)\+(?<digit0>\d{1})(?<lettersdigits0>[A-Z0-9])?(\:\d{1})?\+([A-Z0-9]{1,12})\:([A-Z0-9]{9})\+([A-Z0-9]{0,45})\:([A-Z0-9]{0,45})\:(\d{8})\+(\d{1})(\d{4})?(\d{1})?([A-Z0-9]{1,7})?([A-Z0-9]{3})?([A-Z0-9]{15})?\'$");

string row = @"ABC+1+E522017332:101111757+MAX:MUSTERMANN:16890224+9'";

var match = regex.Match(row);

if (match.Success)
{
    {
        string value = match.Groups["abc"].Value;
        if (value == string.Empty)
        {
            value = "(null)";
        }
        Console.WriteLine(value);
    }

    {
        string value = match.Groups["digit0"].Value;
        if (value == string.Empty)
        {
            value = "(null)";
        }
        Console.WriteLine(value);
    }
}

Possibly names better than abc, digit0, letterdigit0 :-) Names that explain what the digit/letter is!