Re: memory leak in the code?

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sat, 5 Jan 2008 10:30:01 -0800 (PST)
Message-ID:
<ff979cc5-bbad-491a-81db-e178560c0eaf@l1g2000hsa.googlegroups.com>
On Jan 5, 5:21 pm, "Andrew Koenig" <a...@acm.org> wrote:

"Erik Wikstr=F6m" <Erik-wikst...@telia.com> wrote in message

news:zPNfj.2462$R_4.1902@newsb.telia.net...

Yes, but what about if you get a bad_alloc when allocating a? Then you
will try to delete whatever memory that the garbage in a points to. To
prevent this use something like this instead:

try {
 int* a = 0;
 a = new int[N];
 int* b = new int[N];
}
catch (bad_alloc)
{
 delete[] a;
}


Well, the idea is right but the implementation is wrong,
because a will be out of scope in the delete statement.
Moreover, unless a and b are deleted inside the try, the code
will leak memory if it succeeds, because once a and b are out
of scope, there's no further opportunity to delete the memory.

An alternative:

    int* a = 0;
    try {
        a = new int[N];
        int* b = new int[N];

        // do additional work here

        delete[] b;
        delete[] a;
    } catch (bad_alloc) {
        delete[] a;
    }

I agree with you that smart pointers are the way to go here :-)


But not std::auto_ptr, since it does delete ptr, and not
delete[] ptr.

I actually disagree about using smart pointers here.
std::vector seems far more appropriate.

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James Kanze (GABI Software) email:james.kanze@gmail.com
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