When your program allocates memory on the free store, a pointer is returned. It is imperative that you keep a pointer to that memory, because once the pointer is lost, the memory cannot be deleted and becomes a memory leak.

As you pass this block of memory between functions, someone will "own" the pointer. Typically the value in the block will be passed using references, and the function that created the memory is the one that deletes it. But this is a general rule, not an ironclad one.

It is dangerous for one function to create memory and another to free it, however. Ambiguity about who owns the pointer can lead to one of two problems: forgetting to delete a pointer or deleting it twice. Either one can cause serious problems in your program. It is safer to build your functions so that they delete the memory they create.

If you are writing a function that needs to create memory and then pass it back to the calling function, consider changing your interface. Have the calling function allocate the memory and then pass it into your function by reference. This moves all memory management out of your program and back to the function that is prepared to delete it.

DO pass parameters by value when you must. DO return by value when you must. DON’T pass by reference if the item referred to may go out of scope. DON’T use references to null objects.