Dear All,

I have a probably simple question but annoying me a lot.

For example:

std::stringstream ss;
int * p = new int(1);
ss << p; // Output the address
void * q;
ss >> q; // I want to input the address, but give a compilation error.
if (q != NULL)
...

Any way to read an address and see if it is valid?

Thanks a lot!

Shuisheng

shuisheng wrote:

> std::stringstream ss;
> int * p = new int(1);
> ss << p; // Output the address
> void * q;
> ss >> q; // I want to input the address, but give a compilation error.
> if (q != NULL)
> ...

What's the error? The following complete program compiles fine with GCC
4.1.2, VC7 and Comeau 4.3.10.1 Beta (online).

#include <sstream>
#include <iostream>

int main()
{
std::stringstream ss;
int * p = new int(1);
ss << p;
void * q;
ss >> q;
std::cout << q << "\n";

}

But what are you trying to accomplish, anyway? Why don't you put the int
in the stream rather than its address?


--
Christian Hackl

On Jun 6, 10:47 am, Christian Hackl <ha...@sbox.tugraz.at> wrote:
> shuisheng wrote:
> > std::stringstream ss;
> > int * p = new int(1);
> > ss << p; // Output the address
> > void * q;
> > ss >> q; // I want to input the address, but give a compilation error.
> > if (q != NULL)
> > ...
>
> What's the error? The following complete program compiles fine with GCC
> 4.1.2, VC7 and Comeau 4.3.10.1 Beta (online).
>
> #include <sstream>
> #include <iostream>
>
> int main()
> {
> std::stringstream ss;
> int * p = new int(1);
> ss << p;
> void * q;
> ss >> q;
> std::cout << q << "\n";
>
> }
>
> But what are you trying to accomplish, anyway? Why don't you put the int
> in the stream rather than its address?
>
> --
> Christian Hackl

You are right. I have a typo in my testing. I used "void q" rather
than "void* q".

What I am doing is coding a smart pointer. To output it, I output
address and value. In reading, if the address is NULL, it means the
pointer does not point a value.

Thank you so much!

shuisheng wrote:

> On Jun 6, 10:47 am, Christian Hackl <ha...@sbox.tugraz.at> wrote:
>> But what are you trying to accomplish, anyway? Why don't you put the int
>> in the stream rather than its address?
>
> What I am doing is coding a smart pointer.

Is this some kind of exercise? If not, you should have a look at the
smart pointer classes offered by Boost:

http://www.boost.org/doc/libs/1_35_0.../smart_ptr.htm


--
Christian Hackl