compact_real_string Subroutine

  pure subroutine compact_real_string(string)
  !---------------------------------------------------------------------------------------------------------------------------------
  !< author: Izaak Beekman
  !< date: 02/24/2015
  !<
  !< Compact a string representing a real number, so that the same value is displayed with fewer characters.
  !---------------------------------------------------------------------------------------------------------------------------------
  character(len=*),intent(inout) :: string      !< string representation of a real number.
  character(len=len(string))     :: significand !< Significand characters.
  character(len=len(string))     :: expnt       !< Exponent characters.
  character(len=2)               :: separator   !< Separator characters.
  integer(I4P)                   :: exp_start   !< Start position of exponent.
  integer(I4P)                   :: decimal_pos !< Decimal positions.
  integer(I4P)                   :: sig_trim    !< Signature trim.
  integer(I4P)                   :: exp_trim    !< Exponent trim.
  integer(I4P)                   :: i           !< counter
  !---------------------------------------------------------------------------------------------------------------------------------

  !---------------------------------------------------------------------------------------------------------------------------------
  string = adjustl(string)
  exp_start = scan(string, 'eEdD')
  if (exp_start == 0) exp_start = scan(string, '-+', back=.true.)
  decimal_pos = scan(string, '.')
  if (exp_start /= 0) separator = string(exp_start:exp_start)
  if ( exp_start < decimal_pos ) then ! possibly signed, exponent-less float
    significand = string
    sig_trim = len(trim(significand))
    do i = len(trim(significand)), decimal_pos+2, -1 ! look from right to left at 0s, but save one after the decimal place
      if (significand(i:i) == '0') then
        sig_trim = i-1
      else
        exit
      endif
    enddo
    string = trim(significand(1:sig_trim))
  elseif (exp_start > decimal_pos) then ! float has exponent
    significand = string(1:exp_start-1)
    sig_trim = len(trim(significand))
    do i = len(trim(significand)),decimal_pos+2,-1 ! look from right to left at 0s
      if (significand(i:i) == '0') then
        sig_trim = i-1
      else
        exit
      endif
    enddo
    expnt = adjustl(string(exp_start+1:))
    if (expnt(1:1) == '+' .or. expnt(1:1) == '-') then
      separator = trim(adjustl(separator))//expnt(1:1)
      exp_start = exp_start + 1
      expnt     = adjustl(string(exp_start+1:))
    endif
    exp_trim = 1
    do i = 1,(len(trim(expnt))-1) ! look at exponent leading zeros saving last
      if (expnt(i:i) == '0') then
        exp_trim = i+1
      else
        exit
      endif
    enddo
    string = trim(adjustl(significand(1:sig_trim)))// &
             trim(adjustl(separator))// &
             trim(adjustl(expnt(exp_trim:)))
  !else ! mal-formed real, BUT this code should be unreachable
  endif
  !---------------------------------------------------------------------------------------------------------------------------------
  endsubroutine compact_real_string