Re: memory leak in the code?

From:

Andre Kostur <nntpspam@kostur.net>

Newsgroups:

comp.lang.c++

Date:

Sun, 6 Jan 2008 22:25:56 +0000 (UTC)

Message-ID:

<Xns9A1D935325BDnntpspamkosutrnet@209.135.99.21>

=?UTF-8?B?RXJpayBXaWtzdHLDtm0=?= <Erik-wikstrom@telia.com> wrote in
news:zPNfj.2462$R_4.1902@newsb.telia.net:

On 2008-01-05 16:04, George2 wrote:

Hello everyone,

Should I delete memory pointed by pointer a if there is bad_alloc

when

allocating memory in memory pointed by pointer b? I am not sure
whether there will be memory leak if I do not delete a.

[Code]
try {
    a = new int [N];
    b = new int [M];
} catch (bad_alloc)
{
    // if a success, but b fail, should we try to delete[] a here to
avoid memory leak?

}
[/Code]

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;
}

Bad advice: a isn't in scope in the catch clause.

Or use some kind of smart pointer, in which case you do not need to

try-

block since the pointers will free any memory if the exception is

thrown.

auto_ptr<int> a = new int[N];
auto_ptr<int> b = new int[N];

Worse advice. You may not store pointers returned by new[] into an
auto_ptr!