Question

I have to write a function that will get a string and it will have 2 forms:

1. XX..X,YY..Y where XX..X are max 4 characters and YY..Y are max 26 characters(X and Y are digits or A or B)
2. XX..X where XX..X are max 8 characters (X is digit or A or B)

e.g. 12A,784B52 or 4453AB

How can i user Regex grouping to match this behavior?

Thanks.

p.s. sorry if this is to localized

Answer 1

You can use named captures for this:

Regex regexObj = new Regex(
    @"\b                   # Match a word boundary
    (?:                  # Either match
     (?<X>[AB\d]{1,4})   #  1-4 characters --> group X
     ,                   #  comma
     (?<Y>[AB\d]{1,26})  #  1-26 characters --> group Y
    |                    # or
     (?<X>[AB\d]{1,8})   #  1-8 characters --> group X
    )                    # End of alternation
    \b                   # Match a word boundary", 
    RegexOptions.IgnorePatternWhitespace);
X = regexObj.Match(subjectString).Groups["X"].Value;
Y = regexObj.Match(subjectString).Groups["Y"].Value;

I don’t know what happens if there is no group Y, perhaps you might need to wrap the last line in an if statement.