How can I write a to_upper() or to_lower() function in F90?

Question

How does one write a (Intel) F90 function that converts a string into lowercase (or, alternatively, uppercase)? I want to pass a character array to the function and have it retu

Answer 1

Wow -- even though I'd searched for over an hour, immediately after posting this, I found an answer here (under "Miscellaneous Fortran Hints and Tips").

The code I used is as follows (for to_upper):

function to_upper(strIn) result(strOut)
! Adapted from http://www.star.le.ac.uk/~cgp/fortran.html (25 May 2012)
! Original author: Clive Page

     implicit none

     character(len=*), intent(in) :: strIn
     character(len=len(strIn)) :: strOut
     integer :: i,j

     do i = 1, len(strIn)
          j = iachar(strIn(i:i))
          if (j>= iachar("a") .and. j<=iachar("z") ) then
               strOut(i:i) = achar(iachar(strIn(i:i))-32)
          else
               strOut(i:i) = strIn(i:i)
          end if
     end do

end function to_upper

Hope this helps somebody!