Re: Does push_back() do a copy?

Sumit Rajan <>
Thu, 28 Jun 2007 16:44:19 +0530
Angus wrote:

I have a socket class CTestClientSocket which I am using to simulate
load testing.

I create multiple instances of the client like this:

for (int i = 0; i < 5; i++)
    CTestClientSocket* pTemp = new CTestClientSocket(this, ip, port);
// delete pTemp;

When your "delete pTemp;" is uncommented, you're deleting the objects
you have new'd. So, what you have is a vector with pointers that do
point to objects that no longer exist.

Note I have commented out the delete pTemp

Then I send some data to a server like this:

// iterate through collection of clients
for (std::vector<CTestClientSocket*>::iterator it =
    it != m_collClients.end(); it++)

And when you try to play around with pointers that point to non-existent
objects, you're triggering undefined behaviour.

This works if delete pTemp on the Connect is commented out. But I
thought that push_back would make a copy of pTemp. and so I could
then delete pTemp. But if I delete pTemp I get an memory access
problem in the (*it)->Send(byData);

And I have to cleanup at the end. Does push_back NOT do a copy? I am
confused, can someone explain.

Yes, push_back, in your case, pushes a copy of the *pointer*. And then
you destroy the object it points to.


Sumit Rajan <>

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