Quote:

Ok, I've come up with this function... Tell me what you think. Is this going to work, or do I have it all wrong?

Code:

MAGNET* mag_create(STRING* filename,VECTOR* pos,int pole)
{
	MAGNET* tmp= malloc(sizeof(MAGNET));
	tmp->pole= pole;
	switch(pole)
	{
		case POSITIVE:
		{
			ENTITY* ent_post= ent_create("posmagnet.mdl",curpos,phys_objsphere);
			tmp->entity= ent_post;
		}
		case NEGATIVE:
		{
			ENTITY* ent_negt= ent_create("negmagnet.mdl",curpos,phys_objsphere);
			tmp->entity= ent_negt;
		}
	}
	return tmp;
}


I looked up malloc() and sizeof() on Wikipedia. I take it what I'm doing when I write "MAGNET* tmp= malloc(sizeof(MAGNET));" is I'm allocating in memory the data size of the MAGNET struct. How do I use this to keep generating more MAGNET*s? doesn't the first MAGNET* get overwritten by the next one that is generated? Or is there more I should know about malloc()?



No, since youre returning a pointer to an area in the memory which youve already allocated. If you wouldve created a local MAGNET object in a function and then returned THAT magnet as a pointer, then things probably wouldve gone real mad after a while (you wouldve returned a pointer to an area which could have anything in it. Local variables are "cleaned" when they reach the end of their block).

When you do:

MAGNET* tmp= malloc(sizeof(MAGNET));

You callocate a memory, and store the adress in tmp. So when you later on return tmp, you arent returning an "objecT", youre returning a pointer to that space you created (usually something like 00FA0E63). It's more or less just a number that you are returning, but since you store that number as a pointer of MAGNET (i.e. MAGNET* my_pointer = mag_create("lolz", vector(0,0,0), 1) for example), lite-c knows that it has the properties of MAGNET struct.

You can try having this in your main:

Code:

function main()
{
   MAGNET* my_pointer = mag_create("lolz", vector(0,0,0), 1);
   printf("%p", my_pointer); // Prints the location of what the pointer is pointing to.
}


Last edited by Kenchu; 02/01/08 00:11.