Hello could you look at my objects and tell me what is wrong with them? The problem is I am trying to resize my 30x30 vector into a 60x60 vector. But it is wrong the first 30 vectors.

wid_height[0] = 60;
wid_height[1] = 60;

mve.resize(wid_height[0], vector<Entity>(wid_height[1]));

// init_map_entity_cleanup(mve,wid_height);
init_map_home_entity(mve);
init_map_home(cur_map,mve);

Here is image one. Size is 60 as I would like.

Here is image 2 showing all 60.

Here is image 3. There is a huge problem on the first 30 vectors. There vectors only have 30 vectors in them. So the first 30 vectors only have 30 vectors inside them instead of 60 like I need.

Now here is an image of the last 30 vectors 30-59. They have 60 vectors each so they are working properly.

The problem here is that you resize the vector and fill the new spaces with 60-element vectors, but you don't resize the first 30 vectors.

So that is the problem.

Could I solve this by making the vector size 0 then resize it the way I did in the beginning?

Could I solve this by making the vector size 0 then resize it the way I did in the beginning?

It looks like (correct me if I'm wrong), that you're not using a 2D array at all.

Instead, you're using a vector of vectors, which is not a 2D array (it's an array of arrays). C++ doesn't have a built-in 2D vector.

Trying to massage a 'array of arrays' to behave like a 2D array is unnecessary labor. There are two far superior options:

1. Use a 3rd party class (or make one yourself) that actually is a 2D array.
2. Treat a 1D array (like std::vector) as a 2D array.

I usually go with the second option because it's so easy. Memory in RAM is one dimensional. 2D arrays would just line up a extra large 1D array of memory, and do some math to convert 2D coordinates to 1D coordinates. The math is very easy:

std::vector<Type> myArray(width * height);
 
int index = (y * width) + x;
myArray[index] = value;

Easy as pie. Here's the math explanation.

It looks like (correct me if I'm wrong), that you're not using a 2D array at all.

Instead, you're using a vector of vectors, which is not a 2D array (it's an array of arrays). C++ doesn't have a built-in 2D vector.

Trying to massage a 'array of arrays' to behave like a 2D array is unnecessary labor. There are two far superior options:

1. Use a 3rd party class (or make one yourself) that actually is a 2D array.
2. Treat a 1D array (like std::vector) as a 2D array.

I usually go with the second option because it's so easy. Memory in RAM is one dimensional. 2D arrays would just line up a extra large 1D array of memory, and do some math to convert 2D coordinates to 1D coordinates. The math is very easy:

std::vector<Type> myArray(width * height);
 
int index = (y * width) + x;
myArray[index] = value;

Easy as pie. Here's the math explanation.

Thanks for this. I will try to read all this and implement it in my game. I have had more problems with vectors of vectors than anything else.

It looks like (correct me if I'm wrong), that you're not using a 2D array at all.

Instead, you're using a vector of vectors, which is not a 2D array (it's an array of arrays). C++ doesn't have a built-in 2D vector.

Trying to massage a 'array of arrays' to behave like a 2D array is unnecessary labor. There are two far superior options:

1. Use a 3rd party class (or make one yourself) that actually is a 2D array.
2. Treat a 1D array (like std::vector) as a 2D array.

I usually go with the second option because it's so easy. Memory in RAM is one dimensional. 2D arrays would just line up a extra large 1D array of memory, and do some math to convert 2D coordinates to 1D coordinates. The math is very easy:

std::vector<Type> myArray(width * height);
 
int index = (y * width) + x;
myArray[index] = value;

Easy as pie. Here's the math explanation.

I implemented it like you described and it is so much faster. I guess running 10s of thousands of vectors a second is slower than running less than a 100 vectors a second. Thanks.

Np, glad it helped.