// gets the address of a cell range using Excel notation (e.g. A1:B10)
public string GetAddress(CellRange rng)
{
return(rng.IsSingleCell
? GetAddress(rng.r1, rng.c1)
: string.Format("{0}:{1}", GetAddress(rng.r1, rng.c1), GetAddress(rng.r2, rng.c2)));
}