! shellitst.f90  for comparison with shellitst.ada and  shellitst.cc
! shelli.f90  
module sorts
  implicit none
contains
  subroutine shelli(size,arr1,arr2)
    integer, intent(in) :: size
    character (len=3), dimension(:), intent(inout) :: arr1
    real             , dimension(:), intent(inout) :: arr2
    character (len=3) :: temp1
    real              :: temp2
    integer :: i, j, m
    m=size
    do while( m > 1 )
      m=m/2
      do j=1,size-m
        i=j
        do while( i > 0 )
          if(arr1(i) > arr1(i+m)) then
            temp1=arr1(i)
            arr1(i)=arr1(i+m)
            arr1(i+m)=temp1
            temp2=arr2(i)
            arr2(i)=arr2(i+m)
            arr2(i+m)=temp2
            i=i-m
          else
            exit
          end if
        end do
      end do
    end do
    return
  end subroutine shelli
end module sorts
! shellitst.f90
program shellitst
  use sorts
  implicit none
  integer :: i
  character (len=3) :: arr1(20)
  real :: arr2(20)
  data arr1/'MMM','NNN','AAA','CCC','BBB','ZZZ','XXX', &
            'PPP','QQQ','DDD','EEE','FFF','GGG','HHH', &
            'III','JJJ','KKK','LLL','OOO','RRR'/
  data arr2/1.,2.,3.,4.,5.,6.,7.,8.,9.,10.,11.,12.,13.,14., &
            15.,16.,17.,18.,19.,20./
  do i=1,20
    print *,arr1(i),' ',arr2(i)
  end do
  call shelli(20,arr1,arr2)
  print *, 'sorted by name'
  do i=1,20
    print *,arr1(i),' ',arr2(i)
  end do
end program shellitst