Differences between C++ and Java with this-pointer

[Rasti]

Hello,



I am trying to translate a C++ script to Java. Are there any differences
between the C++ this-pointer and the Java this-pointer?



Thank you

Flo


--
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[Victor Bazarov]

Re: Differences between C++ and Java with this-pointer

"Rasti" <member17950@db forums.com> wrote...[color=blue]
> I am trying to translate a C++ script to Java. Are there any differences
> between the C++ this-pointer and the Java this-pointer?[/color]

In Java 'this' is NOT a pointer. There are no pointers in Java.

And, if you have questions on Java, try a Java newsgroup.

Victor

[Joe Gottman]

Re: Differences between C++ and Java with this-pointer


"Victor Bazarov" <v.Abazarov@com Acast.net> wrote in message
news:28cqb.1147 45$e01.418754@a ttbi_s02...[color=blue]
> "Rasti" <member17950@db forums.com> wrote...[color=green]
> > I am trying to translate a C++ script to Java. Are there any differences
> > between the C++ this-pointer and the Java this-pointer?[/color]
>
> In Java 'this' is NOT a pointer. There are no pointers in Java.
>
> And, if you have questions on Java, try a Java newsgroup.
>[/color]

Personally, I think that a question about the similarities and
differences between C++ and Java is on-topic for either C++ or Java
newsgroups. To answer the OP's question, in C++ 'this' is a pointer and in
Java 'this' is a reference, because Java doesn't have pointers. However,
the C++ 'this' pointer is rather strange, because it cannot be reassigned
and cannot be null. It probably should have been a reference. As I
understand it, the main reason it wasn't is because it was invented before
references were.

Joe Gottman

[lilburne]

Re: Differences between C++ and Java with this-pointer

Joe Gottman wrote:
[color=blue]
>
>
> However,
> the C++ 'this' pointer is rather strange, because it cannot be reassigned
> and cannot be null.
>[/color]

void func(A& a);


A* aptr = 0;
func(*aptr);

I think you'll find that within func a's this pointer will
be null.

[Pete Becker]

Re: Differences between C++ and Java with this-pointer

Victor Bazarov wrote:[color=blue]
>
> "Rasti" <member17950@db forums.com> wrote...[color=green]
> > I am trying to translate a C++ script to Java. Are there any differences
> > between the C++ this-pointer and the Java this-pointer?[/color]
>
> In Java 'this' is NOT a pointer. There are no pointers in Java.
>[/color]

There are no pointers, but there is a NullPointerExce ption.

--

Pete Becker
Dinkumware, Ltd. (http://www.dinkumware.com)

[Joe Gottman]

Re: Differences between C++ and Java with this-pointer


"lilburne" <lilburne@godzi lla.net> wrote in message
news:boca9k$1c1 n7t$1@ID-203936.news.uni-berlin.de...[color=blue]
> Joe Gottman wrote:
>[color=green]
> >
> >
> > However,
> > the C++ 'this' pointer is rather strange, because it cannot be[/color][/color]
reassigned[color=blue][color=green]
> > and cannot be null.
> >[/color]
>
> void func(A& a);
>
>
> A* aptr = 0;
> func(*aptr);
>
> I think you'll find that within func a's this pointer will
> be null.[/color]

Derefencing a null pointer, as you do when you call func(*aptr) results
in undefined behavior. You might have a's this pointer null inside the
function call, or you might have a core dump before func is even called.

Joe Gottman