Concatenate using an array formula to result in last name.firstname

Question

We have a form that asks for the students first name and last name. I am trying to using concatenate and an array formula to display "Lastname.Firstname".

I used:

=ARRAYFORMULA(CONCATENATE($B$52:$B,".",$B$52:$C))

but it displays all the last name, a period, then all the first names - looking like this smithjohnsonjackson.johngeorgeharry. What am I doing wrong?

Answer 1

• perhaps try it like this:

  =ARRAYFORMULA(IF(LEN(A:A), B:B&"."&A:A, ))