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I'm trying to add derived objects into an array of base pointers.

My class definition has the following(As this is an assignment it can not be changed):

Base** bases;

Right now I'm using an array of base pointers:

Base** bases=new Base*[2];

And adding elements like so:

bases[0]=new Derived1;
bases[1]=new Derived2;

This works fine if not for the memory leaks that I can't seem to trace. I read I can use vectors for similar purposes with better memory management.

I tried:

vector<Base*>basesV;
basesV.push_back(new Derived1);
basesV.push_back(new Derived2);

It seems to work but how do I 'attach' the vector basesV into my class Base** bases?

Simply bases=basesV; doesn't seem to work. Am I stuck using an array of base pointers?

I also have a function that takes in Base** and dropping the above vector doesn't seem to work as well.

Thanks for any help.

cppStud
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  • If this is an assignment, it seems unlikely that working around the entire thing by hooking in a vector is going to be acceptable. It's a "clever sod" workaround for the constraints of the assignment. It would be better if we could see how you're freeing resources so that we can help you with the memory leak, but you didn't submit a [testcase](http://stackoverflow.com/help/mcve). – Lightness Races in Orbit Apr 11 '15 at 23:40
  • Though I do applaud you for recognising that, in the real world, a vector would make _far_ more sense. In that real world, though, try not to store raw pointers. – Lightness Races in Orbit Apr 11 '15 at 23:41
  • Ya I'm emailing the prof about this. The actual mandate is, you have to use the supplied header files. All we were given is a paragraph on what the program supposed to do, the header files, and a print out of the program in action. vectors still gives me leaks, it isn't as automated as I thought...(see my reply to the answer below). – cppStud Apr 12 '15 at 02:47
  • Well, you're storing pointers. Those pointers are cleaned up. But you still need to clean up the pointees. Typically, as I said, you do not want to store raw pointers. – Lightness Races in Orbit Apr 12 '15 at 13:21
  • You still haven't shown us where you `delete` all these objects....? – Lightness Races in Orbit Apr 12 '15 at 13:21

1 Answers1

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If I understand correctly... 

bases = &basesV[0];

Also make sure your Base destructor is virtual.

Eric Pruneau
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  • Thanks this works for putting the vectors inside function(Base**). Although it doesn't work inside constructors, overloaded operators. Makes sense since it goes out of scope. Having said that I used static for the vector and it works inside constructors and overloaded operators. One thing though how do I make sure to clean up any memory usage. I have a bunch of memory leaks still. Although I admit I have yet to do any cleaning on the vectors that I used inside the aforementioned constructors and overloaded operators. Thanks. – cppStud Apr 12 '15 at 02:42
  • If you have a vector of Base*, you need to delete each and every element of your vector before your vector goes out of scope. The vector destructor *will not* call delete for you on your Base elements. Also, make sure you read this: http://stackoverflow.com/questions/461203/when-to-use-virtual-destructors – Eric Pruneau Apr 12 '15 at 12:22