Correct way to pass object arrays to functions? - c++

Question

So recently, I have been struggling with passing an array to the function (described below). My problem is that when I pass an array only the first element of the array works properly (shown with cout's). And also, object "Enemy" is a child of "Obj".
Creating an array of enemies:
const int eN = 2;
Enemy enemyArray[eN];
for (int i = 0; i <eN; i++) {
enemyArray[i].creating("abc.png", Type::ENEMY);
enemyArray[i].position = Vector2f(x, y);
enemyArray[i].loadChasePoint();
enemyArray[i].number = i + 100;
enemyArray[i].updatePosition();
x += 50; y += 50;
}
The function that includes this array:
void Obj::movement(Vector2f mVector, Obj* b, int objsNumber) {
bool collision = false;
position.x = position.x + mVector.x;
for (int i = 0; i < objsNumber; i++) {
if (!(type == Type::NONE)) {
//if (type == Type::PLAYER) { cout<<"Inside: "<< b[1].getSprite().getPosition().x << endl;} Prints "0"
if (isColliding(b[i])) collision = true;
}
}
if (collision == 1) position.x = position.x - mVector.x;
collision = false;
position.y = position.y + mVector.y;
for (int i = 0; i < objsNumber; i++) {
if (!(type == Type::NONE)) {
if (isColliding(b[i])) collision = true;
}
}
if (collision == 1) position.y = position.y - mVector.y;
}
Calling that function:
//cout <<"Outside: "<<enemyArray[1].getSprite().getPosition().x<<endl; Prints actuall position
playerArray[0].movement(mVector, enemyArray, eN);

Answer 1

the problem is, that you pass an array of type Enemy to a function that expects an array of type Obj. That only works if you pass a single object and if Enemy inherits from Obj. this cannot work for arrays:
sizeof(Obj) is some X. So accessing obj[1] would expect that the second object starts at address adressof(b)+X.
But since your object-array is of type Enemy that has a different size (most probably X+Y) this pointer arithmetics fails at this point since the real address of the second object would be adressof(b)+x+y.
Some variants to solve this:
make b of your movement - function a template arguement
change the b argument to a Obj*-Array and create pointer array from your enemy list before calling the function
I would prefere the first variant. And if your are going to refactor - I would suggest to get rid of the plain pointers and arrays. use std container instead and use their iterators.