Error "std::length"

[Krankzinnig]

I have a vector which is my stack of game states. When I create the first scene, which is just calling ChangeState, I get the std::length error. I understand what this means but I cannot fix it, I don't know why its happening in the first place. This code is working fine in my other project. But when I tried to port it into a static library I got this error when using the library. Here is where the error gets thrown:

 

void Core::ChangeState(StateManager *State) 
{
if(States.empty() != NULL)
{
	States.back()->Destroy();
	States.pop_back();
}

// Store and initialize the new state
States.push_back(State); // Throws std::length error
States.back()->Initialize();
}

 

Here is where I declare the vector.

 

namespace Elixir
{
class StateManager;

class Core
{
	public:
		void Initialize();
		bool Running();
		void Destroy();

		void ChangeState(StateManager* State);
		void PushState(StateManager* State);
		void PopState(StateManager* State);

		void Events();
		void Update();
		void Draw();

		bool Quit;

	private:
		// This is the stack of game states
		vector<StateManager*> States;
};
}

 

Any help would be appreciated. I have reached out to a few people for help on this issue and they all seemed like they didn't know and stopped helping.

[Rick]

Are you sure it's failing on the push_back statement? If I put that code in it fails on States.back()->Destroy(); because I don't think the NULL check you have it the right way to check if the vector has items or not.

 

Do something like if(!States.empty()) instead. Once I do that, this all works for me. I assume you are stepping through your code to see what values are and such?

[Krankzinnig]

Interesting you mentioned using if(!States.empty()) because that's what I had in the first place. But it kept going into that statement. I guess the real problem is that its not empty in the first place. But still don't know how to fix that, because it should be. Yeah, I have stepped through 100+ times. Its a tool I use multiple times a day. Lately its been on the hour.

[Rick]

What compiler are you using? I did this with VS 2005 pro and it worked perfectly once I changed to !empty(). Some implementations of the stl might be slightly different maybe?

 

I assume your entire code is huge? Otherwise post it and we can try it. Might be something going on somewhere else.

[Krankzinnig]

Yeah, the most confusing part is that the same source code works beautifully in my other project. I wanted to port this feature along with many others to a library I can use for my two game titles. Its at this point, when I created a static library that the statemanager stopped working with odd vector issues. So, I scrapped it all out and cleaned my library to try to implement JUST THIS feature. I will let you know soon when I get this done, I can then post more code.

[TheoLogic]

There are some things that will not work as expected:

if(States.empty() != NULL)

Wait whut? If bool != 0? Which warning level are you compiling at. This should warn for conversion. Let's say .empty() returns true, you will do if(true != false), else if(false != false)... The check should be:

if(States.empty() == false)

 

Another thing would be the back() and pop_back() calls. pop_back returns the element, so you can just pop_back()->Destroy() it. Isn't this leaking? State is a pointer, what does Destroy do?

 

What IDE are you using? A possible problem could be if you're using prior to VS2010, that you build the lib in SCL and the test-project (or whatever you name it) in HDI (debug vs release). What actually happens here is that the sizes of vector aren't the same, so hence an error.