gfortran错误:格式字符串要求的非负宽度(1)

The code in question is this:

问题的代码是:

  subroutine PG_TLab_Write(c30,r,d)
  implicit none
  character*30 c30,leftjust
  real*4 r
  integer*4 d,k
  if (d.eq.0) then
    write(c30,'(i30)') nint(r)
  elseif (d.gt.0) then
    write(c30,'(f30.<d>)') r
  else
    k = abs(d)
    write(c30,'(1pe30.<k>') r
  endif
  c30 = leftjust(c30)
  if (d.lt.0) then
    k = index(c30,'E')
    c30 = c30(1:k-1)//'x10\u'//c30(k+1:24)
  endif
  return
  end
  sub