彭书指针链表删除插入问题 - Fortran Coder

[Fortran] 纯文本查看 复制代码



module linklist

implicit none

type::datalink

integer::i

type(datalink),pointer::prev

type(datalink),pointer::next

end type datalink

contains

subroutine outputlist(list)

implicit none

type(datalink),pointer::list,p

p=>list

do while(associated(p))

write(*,*) p%i

p=>p%next

end do

return 

end subroutine

subroutine delitem(item)

implicit none

type(datalink),pointer::item

type(datalink),pointer::prev,next

prev=>item%prev

next=>item%next

deallocate(item)

!if(associated(prev)) prev%next=>next

!if(associated(next)) next%prev=>prev

item=>next

return

end subroutine

subroutine  insitem(pos,item,after)

implicit none

type(datalink),pointer::pos,item

logical::after

if(after) then

item%next=>pos%next

item%prev=>pos

!if(associated(pos%next)) then

!pos%next%prev=>item

!end if

pos%next=>item

else

item%next=>pos

item%prev=>pos%prev

if(associated(pos%prev)) then

pos%prev%next=>item

end if

pos%prev=>item

end if                  

return

end subroutine

end module



program ex1015

use linklist

implicit none

type(datalink),pointer::head,forlatter

type(datalink),pointer::item,p

integer,parameter::s=5

integer::i,n,error

allocate(head)

head=datalink(1,null(),null())

p=>head

do i=2,s

allocate(p%next,stat=error)

if(error/=0) then 

write(*,*) "Out of memory"

stop

end if

P%next=datalink(i,p,null())

p=>p%next

end do

write(*,*) "去掉"

call delitem(head%next%next%next%next)

call outputlist(head)

write(*,*) "插入"

allocate(item)

item%i=30

call insitem(head%next%next%next,item,.true.)

call outputlist(head)

stop

end program

[Fortran] 纯文本查看 复制代码

  write(*,*) "去掉"

  call delitem(head%next%next%next)

  call outputlist(head)

  write(*,*) "插入"

  allocate(item)

  item%i=30

  call insitem(head%next%next%next,item,.false.)

  call outputlist(head)