@Nishaanth,
boiling down to how things work everything is pass by value in C (or you can
argue for hours as Jammy said)
when your function prototype contains a pointer it is simply passed (copied)
the address which was contained in the variable(pointer here) which was
passed during the function call.
use a double pointer as indicated in the above posts.
On Thu, Jan 27, 2011 at 9:28 PM, Jammy <xujiayiy...@gmail.com> wrote:
> call it by reference.
>
> bst *rec = Null;
> insert(rec,5);
>
> void insert(bst *&rec,int data){rec->data = data;}
>
> Or declare it as
> void insert(bst **rec,int data){*rec->data = data;}
> and invoke with insert(&rec,5);
>
> First one is just syntactic sugar to me although you can argue about
> the whole pass-by-value/ref/pointer thing for hours. :)
>
> On Jan 27, 8:03 am, nishaanth <nishaant...@gmail.com> wrote:
> > How can we pass pointers by value. Lets say even if it creates a copy of
> the
> > pointer.
> > The address stored by the pointer is the same. So when we dereference it
> > shouldnt it get updated(as its just a memory address)?
> >
> >
> >
> > On Thu, Jan 27, 2011 at 5:39 PM, ritu <ritugarg.c...@gmail.com> wrote:
> > > Here you are passing record pointer by value.
> >
> > > as you call insert(record, 5),stack frame of insert contains a copy
> > > of record.after this value is modified by calling program,it should
> > > be either returned explicitly to caller program or needs to be passed
> > > by reference,so that calling program refers to it always by address.
> >
> > > On Jan 27, 4:17 pm, nishaanth <nishaant...@gmail.com> wrote:
> > > > Hi guys,
> >
> > > > I have a small doubt regarding pointers and functions.
> >
> > > > Consider the following prototype
> >
> > > > void insert(bst * head, int data);
> >
> > > > This function creates a node and inserts the data in the node. Lets
> say i
> > > > call this function iteratively from main.
> >
> > > > main(){
> >
> > > > bst* record=NULL;
> > > > insert(record, 5);
> > > > insert(record, 8);
> >
> > > > }
> >
> > > > I see that record is not getting modified. Now is this related to
> call by
> > > > value. But since we are passing pointers shouldnt the change get
> > > reflected
> > > > in main.
> > > > isnt is similar to passing an array?
> > > > Enlighten me in this regard. I am tired of segfaults :(
> >
> > > > Regards,
> > > > S.Nishaanth,
> > > > Computer Science and engineering,
> > > > IIT Madras.
> >
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> > --
> > S.Nishaanth,
> > Computer Science and engineering,
> > IIT Madras.
>
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