Is returning auto_ptr from functions wrong/error-prone?

Question

Let's say I'm using std::auto_ptr in my code.*

Is there any danger in returning an std::auto_ptr object?
i.e. Could it result in a memory leak, undefined behavior, etc.? or is it a safe use of std::auto_ptr?

^{*I'm not asking if there is a better substitute (like shared_ptr); I'm specifically asking about the pitfalls of returning auto_ptr itself.}

Answer 1

In general it's safe and can lead to more robust code. It should not lead to a memory leak since the memory pointed to is automatic deleted.

But there are some cases where you have to take care:

• Copies of auto_ptr are not equal!
• Construction of one auto_ptr from another will release the object the first pointer was pointing to

Please see here:

1. http://www.gotw.ca/publications/using_auto_ptr_effectively.htm
2. http://www.cprogramming.com/tutorial/auto_ptr.html

The auto_ptr template class is designed to help manage memory in a semi-automatic way and prevent memory leaks when unexpected events such as exceptions would otherwise have caused the normal cleanup code to be skipped.

(quoted from (2))