npcs.push_back(n);
manager->world->x[abs(n.x)].z[n.z].npc = &npcs[npcs.size() - 1];
Pointers and addresses
Author
Hi,
I have a class that holds all the objects of a class, called Npc.
Then I have a 2d array of Npc pointers, which represent where the Npc's are at.
So when I spawn an Npc, I do this little tidbit:
I all have to say wow you have a tough one. Maybe its because the pointer is some how pointing to a refernce. I don't know am just guessing.
Well, I can't tell you what's going wrong without some description of what's going wrong or some code to see exactly how your manager object is structured. However, you could replace
&npcs[npcs.size() - 1]&npcs.back()
Well, depends on what you mean "wrong". First of all, for instance, this line:
manager->world->x[abs(n.x)].z[n.z].npc
makes me want to take a bath. It compiles and runs but it's just...bad. Better have a World::SetGrid(x,y,npc) function or something like that.
Other than that, you have to realize that std::vector is free to move elements into memory as you add or remove items. So what is now a valid address may not be later. Storing the address of an std::vector item for later use is wrong, unless the vector never resizes, which is not your case. A correct solution would be to make npcs a vector of pointers to NPC.
manager->world->x[abs(n.x)].z[n.z].npc
makes me want to take a bath. It compiles and runs but it's just...bad. Better have a World::SetGrid(x,y,npc) function or something like that.
Other than that, you have to realize that std::vector is free to move elements into memory as you add or remove items. So what is now a valid address may not be later. Storing the address of an std::vector item for later use is wrong, unless the vector never resizes, which is not your case. A correct solution would be to make npcs a vector of pointers to NPC.
Author
Quote:Original post by mikeman
Well, depends on what you mean "wrong". First of all, for instance, this line:
manager->world->x[abs(n.x)].z[n.z].npc
makes me want to take a bath. It compiles and runs but it's just...bad. Better have a World::SetGrid(x,y,npc) function or something like that.
Other than that, you have to realize that std::vector is free to move elements into memory as you add or remove items. So what is now a valid address may not be later. Storing the address of an std::vector item for later use is wrong, unless the vector never resizes, which is not your case. A correct solution would be to make npcs was a vector of pointers to NPC.
Thats the issue!
Sometimes it works and sometimes it doesnt, so it baffled me completely. I am terribly sorry for making you guys guess but my code is getting pretty beastly and its hard to tell what I need to include.
What do you reccommend I use? Would std::list be a better option? or should I use a slightly abstracted array?
Thanks so much!
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