Question

I’ve started a project in C++. Memory management in this language is new to me.

I used to create objects with new () and then pass around pointers and while it worked, it was a pain to debug and people looked at me funny when they saw the code. I am quite proud of the fact that it didn’t leak or segfault (once fixed), but it really was a lot of effort.

list <struct Connection *> users;

struct Connection * accept_connection (const char *name) {
  struct Connection * new_node = new Connection ();
  new_node->_data = ... // whatever, set it up here
  return new_node;
}

struct Connection * new_user = accept_connection (const char *name);
users.append (new_user);

So I have a new strategy for this next version of the project. So far what I am doing is creating objects with new () and assigning them a unique integer ID number. I then store the object in a hashed table using the ID as a key. Now items are stored and passed around by the integer ID number and when you do need to de-reference it, you go to the hash table and it returns you either thing * or NULL. Hence I no longer experience pointer errors but the speed of the code is somewhat reduced.

typedef unsigned long ID_Number;

// create a user and return the ID
ID_Number create_user () {
  ID_Number new_id = assign_unique_id ();
  struct User * node = new User ();
  node->_id = new_id;
  node->_data = ... // whatever, set it up here
  add_to_users_dict (new_id, node);
  return new_id;
}

list <ID_Number> users;

for_each (users.begin(), users.end(), process_user);

void process_user (ID_Number i) {
  struct User * u_ptr = lookup_user_dict (i);
  if (u_ptr == NULL) {
    // not found in dict
    // somehow this guy was deleted
  } else {
    // we can do stuff with this guy
  }
}

Now I am sort of familiar with the basic tenets of programming but being a self-taught hobbyist I am not familiar with the industry practices and tools.
What I am basically asking for, is guidelines on memory management:

1) What am I doing right or wrong?

2) Are there any packages or libraries I can use that would help me?

3) What the the standard practices of the industry?

4) Basically what should I be googling or buying for kindle etc?

Today I usually use Python, it does handle a lot of “back end” stuff for me, but I need C or C++ (I guess I’m using plain C plus the stdc++ libs, I am not quite sure where the overlap between the languages is – I just know g++ compiles it fine) for this one particular project for speed/performance reasons: although I suspect some maths genius could provide algorithmic fixes that would speed it no end, though that’s a separate question.

Answer 1

The best answer I can give, is you shouldn’t use pointers in the traditional way. C++11 has changed the way the programmer deals with memory management.

Rather than explaining things that have already been explained in detail by people far more intelligent than myself I will just provide some links.

The first you should look at is Herb Sutter’s Article Elements of Modern C++ Style
Then check out the video by Bjarne Stroustrup C++11 Style

If you are able to use the new C++11 standard you should, it makes memory management much cleaner than before.