I was making a coordinates class:

class Coords

{

   public:

    

        int x;

        int y;


        Coords( int one, int two)

       {


         x = one;

         y = two;

        }

};

Okay, now I want to make a an array of this objects:

Coords coordinates[7];

Now how would I go about initializing the x and y coordinates of these objects using the constructor?

coordinates[0](10, 10); ?

I don't think so.

I cant even use coordinates[0].x = 10; coordinates[0].y = 10; either.

How would I about doing this?

That array needs to allocate memory for each object as soon as it's declared, so when you do:

Coords coordinates[7];

It will allocate space for 7 Coords and initialize them with the default constructor. But here you have no default constructor - you provided your own which takes parameters, so this line should fail to compile as the compiler doesn't know what to initialize them with. If the size of your array is known, you can initialize them like this:

Coords coordinates[7] = { Coords(1, 2), Coords(7, -2), Coords(4, 0), /* ... */ };

If it isn't, then you can't really do it. In this case what you want is an array of pointers to coordinates, like this, which is closer to what you seem to want:

Coords *coordinates[7]; // can be done, since we're just allocating space for pointers

for (int t = 0; t < 7; ++t) coordinates[t] = new Coords(x, y); // !!

// don't forget to delete them when you no longer need them

Or, better yet, use an std::vector. That's what it's for

TL;DR: classes need to be constructed immediately after allocation. You can't have a "allocated but not created yet" object in C++. But pointers provide a mechanism to achieve the kind of behaviour you are seeking. Also, raw pointers are kind of non-idiomatic in C++. You should be using references to pass objects around, and, if you must, use smart pointers to have better control over your objects. I know it's tempting to do "C with classes" coding but C++ has more features than just classes, it has its own standard library and way of doing things.

And if you want to use a std::vector please add a copy constructor and the == and = operators.

Greetings,

Kim

Sure, of course you can take the one generated by the compiler. Special in this case it makes sence because of the fact that the data type just containes POD-types. But if you don't store the data itself I just remembered the hint from "Effective c++" to have them in place. And maybe I have to rethink about this hint next time :-).

Personally I prefer to use a shared pointer, so here my knowledge seems to be a little outdated.

Greetings,

Kim

Thanks for the infomation, I see your point and do agree.

Kimmi