It's not an assignment. Rather I'm trying to learn back some fortran. I've found a website with some simple problems to do, that's where I got this one. See the first problem of this page : http://www.chem.ox.ac.uk/fortran/. Here's my program : Program vasy implicit none Integer :: C Real :: F C=0 F=0 do while (C<=100) F=(9./5.)*C+32 C+1 write(*,*)C,F end do end program vasy Here's the error I'm getting : " C+1 1 Error: Unclassifiable statement at (1) " I know I didn't have to set F=0, but I tried several things in case the error was there... I can't get rid of the problem. My compiler is goftran and I'm under Ubuntu.