Question about vectors

[Paul Christopher]

I am working on an asteroids program for class and I have it mostly done. The only thing that I'm having problems with is using a vector to assign an id to the asteroids as they are being created. I do not understand how vectors work. Any help would be greatly appreciated.
~I'm using darkgdk and visual C++ 2008 express.~

// Dark GDK - The Game Creators - www.thegamecreators.com

// the wizard has created a very simple project that uses Dark GDK
// it contains the basic code for a GDK application

// whenever using Dark GDK you must ensure you include the header file
#include "DarkGDK.h"
#include <ctime>
#include <vector>

class Asteroids {
public:

	Asteroids() {
		
		//Set Asteroid ID
		ast_id = numObjects;

		//Random Asteroid Location
		srand ((unsigned int) time(0));

		//Variables
		astx = rand() %700;
		asty = rand() %500;
		astx_cnt = 2;
		asty_cnt = 2;
		asrotate = 0;

		numObjects++;
	}

	~Asteroids() {

		numObjects--;
	}

	static int numObjects;

	void Location () {

		//Asteroid Variables
		asmove = 0;
		
		//Asteroid Movement Variables
		dbSprite(ast_id,astx,asty,2);
		astx = astx + astx_cnt;
		asty = asty + asty_cnt;
		astx_inc = astx+1;
		asty_inc = asty+1;

	
		//Rotate Asteroid 1
		asrotate = asrotate +5;
		dbRotateSprite(ast_id,asrotate);
		
		//Place Asteroid Sprite
		if (dbSpriteExist(ast_id))
		{
			
			dbOffsetSprite(ast_id,28,29);

			if (asty >= 450) 
			{
				asty_cnt = (asty_cnt * (-1));
			}

			if (astx >= 650)
			{
				astx_cnt = (astx_cnt * (-1));
			}

			if (asty <=0)
			{
				asty_cnt = (asty_cnt * (-1));
			}

			if (astx <=0)
			{
				astx_cnt = (astx_cnt * (-1));
			}
		}

		Collision(ast_id);
	}

	void Collision(int ast_id){

		int astx1;
		int asty1;

		//Circular Collision Variables
		radius = 28 + 22;
		shipx = dbSpriteX(1);
		shipy = dbSpriteY(1);
		distx = shipx - astx;
		disty = shipy - asty;

		//Circular Collision
		if (dbSpriteExist(ast_id))
		{
			astx1 = dbSpriteX(ast_id);
			asty1 = dbSpriteY(ast_id);
		}

		//set collision for ship and asteroids
		if (dbSpriteExist(ast_id))
		{
			if ((radius * radius) > (distx * distx) + (disty * disty))
			{
				dbDeleteSprite(1);
			}
		}
		
		if (dbSpriteExist(3))
		{
			dbMoveSprite(3,10);

			if (dbSpriteHit(ast_id,3))
			{
				dbDeleteSprite(ast_id);
				dbDeleteSprite(3);
			} 
		}
	}
		

	private:

	//Asteroid Variables
	int asrotate;
	int asmove;
	int ast_id;
	
	int astx;
	int asty;
	
	//Asteroid Movement Variables
	int astx_inc;
	int asty_inc;
	int astx_cnt;
	int asty_cnt;

	//Circular Collision Variables
	int radius;
	int shipx;
	int shipy;
	int distx;
	int disty;


};

int Asteroids::numObjects=5;

// the main entry point for the application is this function
void DarkGDK ( void )
{
	// turn on sync rate and set maximum rate to 60 fps
	dbSyncOn   ( );
	dbSyncRate ( 60 ); 
	dbSetWindowSize(600,400); 

	//Load Images
	dbLoadImage("ship.png",1);
	dbLoadImage("pokeball.png",2);
	dbLoadImage("bullet.png",3);

	//Ship Variables
	int shiprotate = 0;

	//Bullet Variables
	int bulletx;
	int bullety;

	//Place Ship Sprite
	dbSprite(1,300,250,1);
	dbOffsetSprite(1,26,26);
		
	Asteroids ast1;

	
	//Vector
	//vector<Asteroids> asteroid;

	/*for (vector<Asteroids>::size_type numObjects = 0; numObjects < 10; numObjects++)
	{

	}
	*/

	// our main loop
	while ( LoopGDK ( ) )
	{
		ast1.Location();

		//Bullet
		bulletx = dbSpriteX(1);
		bullety = dbSpriteY(1);

		//Ship Movement (stays in the main loop)
		if (dbUpKey())
		{
			dbMoveSprite(1,5);
		}
		if (dbDownKey())
		{
			dbMoveSprite(1,-5);
		}
		if (dbLeftKey())
		{
			shiprotate = shiprotate -5;
			dbRotateSprite(1,shiprotate);
		}
		if (dbRightKey())
		{
			shiprotate = shiprotate +5;
			dbRotateSprite(1,shiprotate);
		}

		if (dbKeyState(0x39))
		{
			dbSprite(3,bulletx,bullety,3);
			dbRotateSprite(3,shiprotate);
			dbOffsetSprite(3,5,5); 
		}
		
		// update the screen
		dbSync ( );
	}

	// return back to windows
	return;
}

[pot]

Hi, how about this.
In initializing,

// you get 10 asteroids in vector.
std::vector<Asteroids*> asteroid;
for (int i=0; i<10; ++i){
	asteroid.push_back(new Asteroids);
}

and, in the loop.

// you can operate each asteroids  
for (unsigned int i=0; i<asteroid.size(); ++i){
	asteroid[i]->location();
}

I used the pointer of 'Asteroids' for vector,
because 'Asteroids' doesn't have method to copy.

[bbgst]

http://cplusplus.com/reference/stl/vector/

[Paul Christopher]

@pot

I see what your getting at. So that would create a total of 10 asteroids to be displayed on screen? Now another question, would that also work for assigning the asteroids a number? (I have a variable used to assign asteroids an id)

//the variable
int ast_id;

//as well as the assignment for it

ast_id = numObjects;