Having a problem with a game that i'm making

[Pyrofan1]

So I made a simple game a few days ago. Now i'm rewriting parts of it to make it better. My problem is that you can shoot at enemies, but when the projectile hits instead of the projectile destroying itself; it resets to 0,0 and then when it hits its target again it crashes.
my AMMO structure

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struct AMMO
{
	SDL_Rect box;
	struct PARTICLESYS *particles; //not used yet
	unsigned char target;
	unsigned char status;
};

my projectile creation code

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struct AMMO *DoAmmo(unsigned char type)
{
	struct AMMO *ammo;

	ammo=malloc(sizeof(struct AMMO));
	switch(type)
	{
		case 1:
		ammo->box.x=player.x;
		ammo->box.y=player.y;
		ammo->box.h=5;
		ammo->box.w=5;
		ammo->status=1;
		ammo->target=ctarget; //current target
		break;

		default:
		break;
	}
	return ammo;	
}

My projectile handling code

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void DrawAmmo(struct AMMO *ammo)
{
	int d;
	if(ammo!=NULL)
	{
		switch(ammo->status)
		{
			case 1:
			ammo->box.h=5;
			ammo->box.w=5;
			SDL_FillRect(screen,&ammo->box,SDL_MapRGB(screen->format,255,0,0));
			if(ammo->box.x>targets[ammo->target]->box.x) ammo->box.x-=3;
			if(ammo->box.x<targets[ammo->target]->box.x) ammo->box.x+=3;
			if(ammo->box.y>targets[ammo->target]->box.y) ammo->box.y-=3;
			if(ammo->box.y<targets[ammo->target]->box.y) ammo->box.y+=3;
			d=distance(ammo->box.x,ammo->box.y,targets[ammo->target]->box.x,targets[ammo->target]->box.y);

			if(ammo->box.x==targets[ammo->target]->box.x&&ammo->box.y==targets[ammo->target]->box.y||d<10)
			{
				printf("ammo hit\n%d\n",d);
				targets[ammo->target]->health-=20;
				if(targets[ammo->target]->status==1) //turn the target hostile if they're currently neutral
				{
					targets[ammo->target]->status=2;
					targets[ammo->target]->color=SDL_MapRGB(screen->format,255,0,0);
				}
				killtarget(targets[ammo->target]);
				free(ammo);
				ammo=NULL;
				printf("ammo freed\n%x\n",ammo); //this stuff happens, but for some reason ammo is getting double free'd
			}
			break;


			default:
			break;
		}
	}
}

code to fire the projectile

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if(playerm>10) //playerm=player mana
						{
							if(ammo!=NULL) //to prevent memory leaks
							{
								free(ammo); 
								ammo=NULL;
							}
							ammo=DoAmmo(1);
							playerm-=10;

							for(count=0;count!=5;count++)
							{
								if(targets[count]->status==3) targets[count]->status=2; //unfreezes all frozen targets
							}
						}

As far as i can tell the problem is that the projectile is getting double free'd somewhere in the DrawAmmo Function, but that shouldn't happen as ammo is getting set to NULL and i have if()s around all my Free()s

[DeletedAccount]

Hi,

Few observatios

1) Have you tried debugging with a debugger

2) Your collision detection is rather clumsy . The first check is not really required if you have written the distance function properly . Use rectangle based method for detecting collision and avoid floating point math when possible .

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if(ammo->box.x==targets[ammo->target]->box.x&&ammo->box.y==targets[ammo->target]->box.y||d<10)

3) and you have a basic chasing algorithm implemented in your first game -- good job

4) you should try enums instead of hard coding values in code , that leads to more readable code
Regards
Shrek