stringtool_obj_RemoveExtension Function

    pure function stringtool_obj_RemoveExtension(filename) result(val)
      !> Removes file extension from filename while preserving
      ! time in scientific notation and dots in paths.
      character(len=*), intent(in)  :: filename                                !! File name
      character(len=:), allocatable :: val                                     !! Returned string with extension removed
      ! Work variables
      integer :: last_slash
      integer :: i,n
      logical :: is_sci_dot

      val = trim(adjustl(filename))
      n = len(val)

      ! Find last path separator to avoid dots in directory names
      last_slash = index(val, '/', back=.true.)

      ! Scan backwards from the end of the string to find the TRUE extension dot
      do i = n, last_slash + 1, -1
          if (val(i:i) == '.') then

              ! Assume this is NOT a scientific notation dot unless proven otherwise
              is_sci_dot = .false.

              ! Check if this dot is followed by the ES12.4 pattern (e.g., .0000E+01)
              ! The pattern ".0000E+" is 7 characters long.
              if (i + 6 <= n) then
                  if (val(i+1:i+1) >= '0' .and. val(i+1:i+1) <= '9' .and. &
                      (val(i+5:i+5) == 'E' .or. val(i+5:i+5) == 'e') .and. &
                      (val(i+6:i+6) == '+' .or. val(i+6:i+6) == '-')) then
                      is_sci_dot = .true.
                  end if
              end if

              ! If it's a real extension dot (not part of the time string), truncate and exit
              if (.not. is_sci_dot) then
                  val = val(:i-1)
                  return
              end if
          end if
      end do

      return
    end function stringtool_obj_RemoveExtension