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Closed 12 years ago.
I am really confused about memory management in C++. What is the best reference (book or web) that deals with memory allocation, stack, heap, free store and scope & lifetime of variables.
Is there any resource that contrasts C++ memory allocation basics with that in C#?
The C++ FAQ deals with memory management issues extensively.
I strongly recommend Expert C Programming: Deep C Secrets for learning all about these little details. It's got nothing to do with C++, but you'll learn almost everything you asked about :) and the writing is superb, which is pretty rare with C++ books.
RAII in conjunction with smart pointers (std::unique_ptr, std::shared_ptr) is basically all you will need. If you stick with it you will get exception safe, memory leak free code :)
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Closed 9 years ago.
I am from JAVA so please please guide me if i am wrong.
In Java we mostly use a singleton class and create all the class objects thought the singleton class.
What about in c++?
I know we can use singleton but mostly while going through most of the stack overflow questions. Most of them says it's not good to use singleton in c++
Can you recommend some book or some project which will be easy to understand?
Whether you're writing in C++ or Java singletons have many, bad implications.
They make it very difficult to test as their static nature preculdes late binding to, say, sway a real database with a stub that's quicker and has fewer depencies.
They also provide a fig leaf for global variables, trying to make them masquerade as a good design decision. Take a look at the alternatives, it'll pay off in a better design. You may want to look into dependency injection for ways to design a more testable system without singletons.
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Closed 10 years ago.
I am having serious issues in the heap because in the previous programs, I did not delete the pointers variables. How do I clean the memory space/heap now to run the current programs?
Kill the offending processes, then the OS will clean up their memory for you.
For every allocation you make on the heap with new/malloc or other such functions you must delete/free the resource that you have used when you are finished with it.
C++ makes available some easy ways to do this with constructors allocating resources and destructors free'ing the resource.
Then there are lots of clever ways with std::auto_ptr or even other smart pointers that can help you manage this.
Basically you allocated it - so it is your job to free it.
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Closed 10 years ago.
I have a strategy pattern, and would like to run it in a main loop in a game for example. The problem is there will be a memory leak If I'm not deleting the instance, and I also would like to use that instance somewhere else. How can I deal with memory allocation/deallocation in a strategy pattern.
CompressionContext *ctx = new CompressionContext();
//we could assume context is already set by preferences
ctx->setCompressionStrategy(new ZipCompressionStrategy());
//get a list of files
ctx->createArchive(fileList);
Use an std::shared_ptr<CompressionContextBase> instead of a CompressionContextBase* (i.e. a raw pointer).
Edit: This is just a suggestion, based on the information you provided, there may be other smart pointer implementations with different semantics, such as e.g. unique_ptr, which might be more suited. As #akappa suggests, you may want to read up on the topic more, to make a better decision -- again, based on the information in the question, you probably want a shared_ptr but there might be additional considerations you omitted.
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Closed 12 years ago.
So I mean like it tries to educate it self and collects some data... Are there any such points/feilds in encoding part of ffmpeg (that I hope can be disabeld)?
BTW: My problem is simple: I looked thrue out all my code. It seriosly looks like it is some part of my ffmpeg windows build leaks memory a littel... all the time while I am encoding... So I hope ffmpeg is just triing to learn so that I would be able to tell ti not to learn!)
FFmpeg libraries use a very object-oriented design. All memory allocated should be kept track of in the context structures and freed when the relevant context is destroyed. There may be some one-time allocation and initialization of constant global data which one could call a "leak", but I believe that was all replaced with static const tables to facilitate better use of shared memory and eliminate memory leaks associated with dynamic loading. If you really think it's leaking (and if you care), you need to use some memory debugging tools to identify where the leaks might be and coordinate finding/fixing them with the developers.
If what you mean is that during a single encode, memory usage grows slightly, this is probably normal and to be expected. It shouldn't be much, and the memory should all be released when the encoding context is freed.
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Closed 12 years ago.
plz Send me the answer of the following question.
what is the persistent c++ system?
A persistent C++ system could be a software layer or an entire ORM responsible for the persistence of C++ objects in a database,
The persistent C++ system doesn't mean anything out of context.
A persistent C++ system uses persistent C++ objects.
Those are objects that continue to exist after the method exits.
For example see persistent C++
Sounds like homework, but:
Persistence in C++ is generally usually handled by serialization.