Velocity Reviews > Given only a pointer to a node to be deleted in a singly linked list, how do u delete it?

# Given only a pointer to a node to be deleted in a singly linked list, how do u delete it?

ac.c.2k7@gmail.com
Guest
Posts: n/a

 04-14-2007
Hello Everyone,

The solution to this is to copy the data from the next node into this
node and delete the next node!.
1. But if the node to be deleted is the last node. Then what should we
do ?
2. If the list is Head node?
3 If the list is circular then what all conditions we need to check?

Thanks,
kaka

Richard Heathfield
Guest
Posts: n/a

 04-14-2007
http://www.velocityreviews.com/forums/(E-Mail Removed) said:

> Hello Everyone,
>
> The solution to this is to copy the data from the next node into this
> node and delete the next node!.

No, the solution is to re-design the interface to the deletion routine
so that you get sufficient information supplied to you to enable you to
do the job properly.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

Karl Malbrain
Guest
Posts: n/a

 04-14-2007
On Apr 14, 10:38 am, "(E-Mail Removed)" <(E-Mail Removed)> wrote:
> Hello Everyone,
>
> The solution to this is to copy the data from the next node into this
> node and delete the next node!.

Not necessarily. You could mark the node for future deletion and then
check if the next node was marked previously and delete that one since
you have the pointer to it.

> 1. But if the node to be deleted is the last node. Then what should we
> do ?

Just mark it.

> 2. If the list is Head node?

Since you have the pointer to it, you can delete it immediately.

> 3 If the list is circular then what all conditions we need to check?

You need to check if the head node is the next node and adjust it
accordingly.

Hope this helps....karl m

Karl Malbrain
Guest
Posts: n/a

 04-14-2007
On Apr 14, 10:38 am, "(E-Mail Removed)" <(E-Mail Removed)> wrote:
> Hello Everyone,
>
> The solution to this is to copy the data from the next node into this
> node and delete the next node!.
> 1. But if the node to be deleted is the last node. Then what should we
> do ?

If you use an empty "stopper" node at the end of your list, you'll
never get the "last" node for deletion and your solution works fine.

> 2. If the list is Head node?

Set a new head and delete it.

Hope this helps, more..... karl m

=?ISO-8859-1?Q?Erik_Wikstr=F6m?=
Guest
Posts: n/a

 04-14-2007
On 2007-04-14 19:38, (E-Mail Removed) wrote:
> Hello Everyone,
>
> The solution to this is to copy the data from the next node into this
> node and delete the next node!.

Scan the list from head until you find the node to delete and delete it
just like you'd delete any node in a single-linked list.

--
Erik Wikström

monty
Guest
Posts: n/a

 04-15-2007
HI friends
storing two pointers
the current node and previous node .If current node
becomes deletion node
delete it and attach the previous node to the next of
current node.

1 if header node is deletion node then simply delete it and point the
next node to be the header node.
2If last node is deletion node above process will work
3. In case of circular list move until current node becomes deletion
node.Remember start from previous note assignment thru

Richard Heathfield
Guest
Posts: n/a

 04-15-2007
monty said:

> HI friends
> Start from the header node and

In other words, change the spec. Absolutely right.

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

Snis Pilbor
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Posts: n/a

 04-15-2007
On Apr 14, 1:38 pm, "(E-Mail Removed)" <(E-Mail Removed)> wrote:
> Hello Everyone,
>
> The solution to this is to copy the data from the next node into this
> node and delete the next node!.
> 1. But if the node to be deleted is the last node. Then what should we
> do ?
> 2. If the list is Head node?
> 3 If the list is circular then what all conditions we need to check?
>
> Thanks,
> kaka

People have already pointed out various ways to do this, so I won't
further elaborate on them; what I will do is point out what's wrong
with the above.
In any program of significant size, you're liable to have other
pointers besides those pertaining to the linked list itself, pointing
to the "next node" (the one which your solution says to delete).
You'd have to painstakingly find every last thing which can point to a
node in your list, and handle it accordingly, or else after the "next"
node is deleted, you may have other pointers floating around still
pointing to it.

Example: your "nodes" are soldiers in a battlefield videogame. The
list is periodically run through to make all the soldiers do their
thing. But the battlefield also has machineguns, and each machinegun
actively targets a specific soldier-- which is handled by having the
machinegun structure include a "struct soldier_data *target." A
soldier dies, who was being targeted by a machinegun; the soldier is
deleted from the list in the method you described, and now the
machinegun's "target" pointer is pointing to undefined data. When it
comes time for the machinegun to shoot, your program crashes (in best
case scenario- or does even worse things, possibly).

R Smith
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Posts: n/a

 04-16-2007
"(E-Mail Removed)" <(E-Mail Removed)> wrote in
news:(E-Mail Removed) oups.com:

> Hello Everyone,
>
> The solution to this is to copy the data from the next node into this
> node and delete the next node!.
> 1. But if the node to be deleted is the last node. Then what should we
> do ?
> 2. If the list is Head node?
> 3 If the list is circular then what all conditions we need to check?
>
> Thanks,
> kaka
>

This is really simple. If you start from the beginning of the list:

if (begin_ll == delete_node) /* single entry */
{
free (begin_ll); /* and any data */
begin_ll = (LNK_LST_NODE *) 0;
return;
}

/* otherwise */

for (prev = begin_ll; prev; prev = prev->next)
{
node = prev->next;
if (node->next == delete_node)
{
prev->next = node->next->next; /* whether it's NULL or not
doesn't matter */
free (delete_node); /* free any malloc'd data first*/
break;
}
}

It will either become the end of the list or will simply point to the node
after the delete_node.

It helps to visualize this (though I've been out with the gang tonight and
the vision is a little sketchy, but I believe it works). Draw the nodes on
a piece of paper and think it through.

Bill Pursell
Guest
Posts: n/a

 04-16-2007
On Apr 16, 3:52 am, R Smith <(E-Mail Removed)> wrote:
> "(E-Mail Removed)" wrote the subject line and:

> > The solution to this is to copy the data
> > from the next node into this
> > node and delete the next node!.

>
> This is really simple. If you start from
> the beginning of the list:

In the original statement of the question, you don't have