Sending arrays of variable size

[kingoftheconnors]

Sending arrays of variable size

[kingoftheconnors]

After some experimentation, I figured out that it wasn't the pointer that was the problem, it was the initialization of the array!

GameStateMessage *message = (GameStateMessage*)client.CreateMessage(MessageType::GAME_STATE_MESSAGE);
message->arr = new int[global::MAX_PLAYERS];
for (int i = 0; i < global::MAX_PLAYERS; i++) {
    message->arr[i] = i*2;
}
client.SendMessage(message, UNRELIABLE_UNORDERED_CHANNEL);

This is the client sending the array. Obviously, it declares the array, but when reading the array, it never got initialized!

So this example worked if forcing the array to be size 5:

struct GameStateMessage : public Message
{
    int *arr = new short[5]; // Initalized for both sender and reciever

    GameStateMessage() {}

    template <typename Stream> bool Serialize( Stream & stream )
    {
        for (int i = 0; i < 5; i++) {
            serialize_int(stream, arr[i], -390, 3700);
        }
        return true;
    }

    YOJIMBO_VIRTUAL_SERIALIZE_FUNCTIONS();
};

So, pointer array works, right? Well, the main problem is how the reader will know what the length will be. That's the entire point, right?

Taking some inspiration from the serialize_string function, we just need to send the size FIRST! And then use that to dynamically allocate the received array:

struct GameStateMessage : public Message
{
    const int MAX_ARRAY_SIZE = 64;  // This is our theoretical highest array size
    int *arr;
    int length;

    GameStateMessage() {}

    template <typename Stream> bool Serialize( Stream & stream )
    {
        serialize_int( stream, length, 0, MAX_ARRAY_SIZE );
        if (Stream::IsReading)
        {
            arr = new int[length];
        }
        for (int i = 0; i < length; i++) {
            serialize_int(stream, arr[i], -390, 3700);
        }
        return true;
    }

    YOJIMBO_VIRTUAL_SERIALIZE_FUNCTIONS();
};

And this works! Tries sending {1, 2, 4, 6, 8}, gets back out {1, 2, 4, 6, 8}

Thanks @Green-Sky for the little extra push to figure this out!

[Green-Sky]

I recommend running with a debugger.

[Green-Sky]

Remember to free the memory, or you have a memory leak in your hands.
Personally I would just go with std::vector.

[kingoftheconnors]

Ah, good point! Thanks!

Since this issue is taken care, I'll close it.