to_lower Function

elemental function to_lower(str) result(lcstr)

   !> Input string
   character(len=*), intent(in) :: str

   !> Lowercase version of string
   character(len=len(str)):: lcstr

   integer :: ilen, iquote, i, iav, iqc
   integer, parameter :: offset = iachar('A') - iachar('a')

   ilen = len(str)
   iquote = 0
   lcstr = str

   do i = 1, ilen
      iav = iachar(str(i:i))
      if (iquote == 0 .and. (iav == 34 .or.iav == 39)) then
         iquote = 1
         iqc = iav
         cycle
      end if
      if (iquote == 1 .and. iav==iqc) then
         iquote=0
         cycle
      end if
      if (iquote == 1) cycle
      if (iav >= iachar('A') .and. iav <= iachar('Z')) then
         lcstr(i:i) = achar(iav - offset)
      else
         lcstr(i:i) = str(i:i)
      end if
   end do

end function to_lower