Can a memory block allocated by using operator new/malloc persist beyond end of program execution? [duplicate]

Answer 1

You have to worry about it because imagine that you were allocating a lot of memory in many many places and NOT freeing it. Once memory is allocated it occupies a portion of memory that cannot be allocated anymore. This will result in the amount of available memory getting smaller and smaller each time because you are failing to free it. At some point the memory will be exhausted. Even if the memory is freed at program termination, imagine that your program runs for several weeks at a time, constantly allocating memory but never freeing it. Memory is a finite resource and you need to be responsible when using dynamic allocation.

Answer 2

You do not need to release the memory back to the OS before the program exits, because the operating system will reclaim all memory that has been allocated to your process upon the termination of the process. If you allocate an object that you need up to the completion of your process, you don't have to release it.

With that said, it is still a good idea to release the memory anyway: if your program uses dynamic memory a lot, you will almost certainly need to run a memory profiler to check for memory leaks. The profiler will tell you about the blocks that you did not free at the end, and you will need to remember to ignore them. It is a lot better to keep the number of leaks at zero, for the same reason that it is good to eliminate 100% of your compiler's warnings.

Answer 3

1) Free your memory when you request if off the heap. Memory leaks are never a good thing. If it doesn't hurt you now, it likely will down the road.

2) There is no guarantee by C or C++ that your OS will clean up the memory for you. You may be programming some day on a system that, in fact, does not. Or worse, you may be porting code in which you didn't care about memory leaks to this new platform.