Is it possible to have memory leak without new keyword?

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What I understand the reason for memory leak is because an object is created on the heap and is not cleaned by using the delete keyword. So if in a project a class is always initialized in the stack there will be no memory leaks for this class. Is it possible to have memory leaks for a class if the objects of this class are always initialized without the new keyword?

For example, I have a class CStudent and in my code I always use CStudent stu to initialize this class. I have some vectors to store objects of CStudent but I define them as vector<CStudent>. I never use new keyword to create a CStudent object. So is it possible to have memory leaks of CSudent objects?

Posted 24-May-11 14:03pm

Raptor81

Updated 24-May-11 15:41pm

v5

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Sergey Alexandrovich Kryukov 24-May-11 21:01pm

You question has nothing to do with C++/CLI? Do you also need advice about memory leak in managed platform? (Yes, you can get memory leak in managed platform as well.)
If not, remove C++/CLI tag.
--SA

[no name] 25-May-11 5:34am

One should release all WINDOWS HANDLE for objects been used.

4 solutions

Solution 4

http://msdn.microsoft.com/en-us/library/x98tx3cf(v=VS.80).aspx[^]

check this...

Posted 30-Nov-11 17:45pm

Selva K

v2

Solution 3

In fact, you take the memory and you should free the memory.
You can use different debuggers to find out where there is a leak and then think about its removal. I use deleaker? as my debugger.

Posted 30-Nov-11 9:22am

Mast Avalons

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Mark Salsbery · Accepted Answer · 2011-05-24T14:55:00

Solution 1

Your vectors are probably using heap memory to allocate space for your CStudent objects so you could probably still find a way to leak memory.

Why do you ask?? Depending on the size of the objects and how many there is, the stack may not be the appropriate place for them. Plus your stack based objects only last for the duration of the function they are created in.

Posted 24-May-11 14:55pm

Mark Salsbery

Comments

Sergey Alexandrovich Kryukov 24-May-11 21:16pm

I agree, my 5.
My answer actually answers original question: if memory leak is possible without new.
I overview the situations when it happens, please see.
--SA

Mark Salsbery 24-May-11 21:19pm

Thanks, and a 5 back at you. I did see your post!

Sergey Alexandrovich Kryukov 24-May-11 21:21pm

Sure, and thank you.
--SA

Sergey Alexandrovich Kryukov · Accepted Answer · 2011-05-24T15:15:00

Yes, you can have a memory leak without the key word new.

The example you explain does not look like it can cause a memory leak if the vector is cleaned up correctly, but there can be different scenarios. I would classify them into two classes: memory allocation below the new level and above the new level. By new level I mean memory allocation/deallocation embedded in the language.

Below: C++ new/delete is implemented on top of OS platform. Language binding with OS is usually based on allocation and deallocation of system heap. For optimization and reduce of fragmentation a sub-allocator can be used: a block of memory can be allocated on the system heap in big chunks; and this memory is sub-allocated for smaller objects. Your code can also use language binding to the OS directly and allocate memory without using new. Is this memory is not properly reclaimed, memory leak may occur. Also, some OS API can allocate memory indirectly. It requires some clean-up OS calls. If not cleaned-up correctly, such calls can cause some memory leaks. Such indirect memory leak cause by incorrect use of OS binding is closely related to the problem of resource leak.

Above: you can use third-party libraries which can allocate memory at the language level (new) or at the level of OS. If you make bugs in using of such libraries or if the libraries have bugs, it can cause memory leak. You may not be able to detect the presence of new in such libraries when their source code is not available to you.

One practical note: very typical source of memory leaks as a result of programming bug is the failure to reclaim memory in case of exception. Proper use of try-finally construct helps to avoid such situations.

—SA