what do you think is wrong with this?

#include <iostream>

int foobar (int *pi1)
{
*pi1 = 1024;
return *pi1;
}

int main ()
{
int *pi2 = 0;

int ival = foobar (pi2);

return 0;
}

* a R T u n:[color=blue]
> [homework][/color]

See <url: http://www.parashift.com/c++-faq-lite/how-to-post.html#faq-5.2>.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

a R T u n wrote:[color=blue]
>
> what do you think is wrong with this?
>
> #include <iostream>
>
> int foobar (int *pi1)
> {
> *pi1 = 1024;
> return *pi1;
> }
>
> int main ()
> {
> int *pi2 = 0;
>
> int ival = foobar (pi2);
>
> return 0;
> }[/color]

dereferencing a null pointer has undefined behaviour.

--
Karl Heinz Buchegger
kbuchegg@gascad.at

>>Is it homework or quiz?[color=blue][color=green]
>> int *pi2 = 0;[/color][/color]
Okey Your address is null.[color=blue][color=green]
>> *pi1 = 1024;[/color][/color]
I am giving you 1024 doller at your address.(But Postmaster is not
accepting the letter with null address.)[color=blue][color=green]
>>return *pi1;
>>int ival = foobar (pi2);[/color][/color]
You haven't get it. Why?
You forget to given your address.
First construct your house either on stack or on heap, then give the
address of that.
int pi = 0; /// Now &pi is valid address of your house pi constructed
on stack.
int ival = foobar (&pi);

just none... only a newbie in pointers...

----- Original Message -----
From: "a R T u n" <muratartun@gmail.com>
Newsgroups: comp.lang.c++
Sent: Tuesday, July 26, 2005 1:26 AM
Subject: Re: pointer error...

[color=blue]
> just none... only a newbie in pointers...
>[/color]

Did you understand the answers?

int *p = 0; // Defines a pointer pointing to "nothing" (a NULL pointer)

You can't use this before you point it to some place to actually store the
interger.

*p = 1024; // Error, p isn't pointing to anything your program owns.

p = new int; // allocates sizeof(int) memory, p now "points" to it.

*p = 1024; // Now 1024 goes into those sizeof(int) bytes that were
allocated.