Dynamic range

[bines]

I would like formula that will give range of the cells there are in him data in the same a moment ,For example I define a range A1: G20 .But the last cell he until c15 and the formula needs to give A1:A15.
A formula( function) needs to return the cell or range reference pointed to by RangeRef as text like A1:C15
If it's possible also to receive in User Defined Functions .

Thanks