Question

Does C# have built-in support for parsing strings of page numbers? By page numbers, I mean the format you might enter into a print dialog that’s a mixture of comma and dash-delimited.

Something like this:

1,3,5-10,12 

What would be really nice is a solution that gave me back some kind of list of all page numbers represented by the string. In the above example, getting a list back like this would be nice:

1,3,5,6,7,8,9,10,12 

I just want to avoid rolling my own if there’s an easy way to do it.

Answer 1

Should be simple:

foreach( string s in '1,3,5-10,12'.Split(',') )  {     // try and get the number     int num;     if( int.TryParse( s, out num ) )     {         yield return num;         continue; // skip the rest     }      // otherwise we might have a range     // split on the range delimiter     string[] subs = s.Split('-');     int start, end;      // now see if we can parse a start and end     if( subs.Length > 1 &&         int.TryParse(subs[0], out start) &&         int.TryParse(subs[1], out end) &&         end >= start )     {         // create a range between the two values         int rangeLength = end - start + 1;         foreach(int i in Enumerable.Range(start, rangeLength))         {             yield return i;         }     } } 

Edit: thanks for the fix 😉