Re: clarification on pointer use
On 2/22/2012 7:37 AM, Ruby Stevenson wrote:
I have a newbie question. Let me try to use an example to illustrate:
I have some Event class defined, and I could save a collection of
event objects in two ways:
method 1:
vector<Event*> event_vec;
....
Event * event = new Event();
event_vec.push_back(event);
method 2:
vector<Event> event_vec;
....
Event event;
event_vec.push_back(event)
So one is store a pointer to event; the other store a copy of the
event in a container.
what are the implications between the two choices? when would be the
proper use of one instead of the other?
Implications are the same as storing a copy versus storing a pointer to
the original object anywhere else. Changing the copy has no effect on
the original object, so if you expect to pass it around, the changes
have to be carefully tracked. Storing a pointer puts the responsibility
of maintaining the lifetime on you, whereas a copy lives its own life
under the control of the container in which it's stored. Storing a copy
could require more memory and be generally slower than storing a
pointer... I am sure there are other differences, and you can probably
find lots of interesting stuff about those in any decent book on C++.
What book are you currently reading?
V
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