Memory access error with STL composed types

[tuxman]

Hi all.
First of all let me apologize by my english.
I've googled a lot about my problem, but I had not find anything conclusive.
I have the following piece of code:

vector < map < int , char * > > bank;
bank . reserve ( 10 );
if ( bank [ 0 ] [ 0 ] == "a" ) //Memory access error (Access violation at address #blabla)

which give me the error indicated in comment.
So, to test, I included the following line before "if", and the error changes to that line

bank [ 0 ] [ 0 ] = "b"; //Same error

Finally, the following inserted in place of the line above, works.

map < int , char * > data;
data [ 0 ] = "a";
bank . push_back ( data );

But this is hardly an option to me. Mainly because I need, most of times, to test the variable "bank" (even the NULL address existence, which tells me that new item insertion is ok) before I can decide what to do. Beside that, that association grows interactively.
As I can see, it seems a problem with map allocation.
So, my exactly question is how can I use this type of association ( vector < map < type1 , type2 > > ) without get into Mermory access violation errors? Is there a way to previously initialize that association in a manner that allow me to insert new element just doing

bank [ i ] [ j ] = "some"

even after the limits previously defined (growing the association)?
Please excuse me if this is trivial, but I'm new to STL.
I appreciate any helps.
Thanx in advance.

[weaknessforcats]

I see the vector named bank.

I do not see that this is a two-dimensional array so your bank[x][y] syntx just will not work.

If you are new to STL, then this vector is a very advanced one indeed for you to be using. Maybe you could tell me what youare trying to do. It may be you are doing things the hard way.

[tuxman]

In fact, I've change it a bit. What I have is vector < map < int , Object * > >, but I think it does'nt matter. What I need is exaclty what I try to represent.An array with each element having an associative array. To clarify: each position of the array represent a level. In each level I've a group of cells (of a grid) that I must inspect and I use their index as a key in associative array.
You say that bank [ i ] [ j ] does'nt look like a bidimensional array for you. But, in fact, I can get the array element value when I do var = bank [ i ] [ j ] (of course, when I use push_back first). So, it is a lot confusing to me. Any ideas?
Thanx.

[tuxman]

I forgot to say something very important. I do not know previously, the size of array (vector) or associative array (map). They grow interactively in execution time and their size may vary in a wide range ( to few hundreeds from hundreeds of thousands and even million).

[weaknessforcats]

What I need is exaclty what I try to represent.An array with each element having an associative array.

This would be a vector where each element is itself a vector.

vector< vector<Object*> > bank;
 

Now the bank[i][j]syntax will work.

If you are accessing by a key then you may want a map where each element is itself another map.

map< int, map<int, Object*> > bank;
 

Here you would specify a key to get a map and then specify another key to get an Object* from that second map.

Here you could use bank[i][j] to get on Object*.