Re: Deleting a passed-by-reference object in a function

From:

"M. Shoaib Surya" <shoaibsurya@hotmail.com>

Newsgroups:

microsoft.public.vc.language

Date:

Wed, 12 Mar 2008 20:51:29 +0500

Message-ID:

<uxxqtmFhIHA.1996@TK2MSFTNGP03.phx.gbl>

Thanks for you reply Uli. Agree with both of your suggestions. It's not part
of some new code that I am writing, just something from some already written
code, and it was not that simple but translated to some what this case,
which was indeed a surprise in itself :)

Shoaib.

"Ulrich Eckhardt" <eckhardt@satorlaser.com> wrote in message
news:5u7la5-b75.ln1@satorlaser.homedns.org...

M. Shoaib Surya wrote:

Is it okay to delete an new'ed object in the function that has been
passed-by-reference.

Please check the statement "delete pCalled;" in the following code
snippet.

void Test(int& i)
{
    int* pCalled = &i;
    printf("Address in Called: %d\n", pCalled);
    delete pCalled;
}

int main()
{
    int* pCaller = new int(10);
    printf("Address in Caller: %d\n", pCaller);
    Test(*pCaller);
}

The thing is that it is running fine in VC and the pointer also has the
same value. But, what I am wondering is that is it possible that this is
a
platform-specific implementation of the compiler and this code might
break
on other platforms, or is it a defined behavior and perfectly legal in
C++?

This code is perfectly legal. However (I guess you know that yourself
though) it is also really bad code because it violates the principle of
least surprise.

Suggestion:
- Don't delete it inside the function.
- Use a std::auto_ptr<int> in order to clearly document that ownership is
transferred.

Uli

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