suitable data struct needed

[whocares21]

hey guys. im implementing a program. and i need a data structure (like queue) which should has these features;
for example user inputs an integer => x;
I have to create something like an array => array[100][m]

this is easy but i will have to shift all the elements to the next row before add a new element.

lets say:

m=3;
arr[0][0]=0;
arr[0][1]=0;
arr[0][2]=0;

then im gonna add a new serie, lets say 1,2,3. then my array should be like this:

arr[0][0]=1;
arr[0][1]=2;
arr[0][2]=3;
arr[1][0]=0;
arr[1][1]=0;
arr[1][2]=0;

(like shifting)
and the last elements of array should be deleted. i mean
arr[100][0..m]=arr[99][0..m]

- If I use array, I have to run 2 for loops for shifting before adding (this is a huge problem for me and lots of time wasting)
- If I use queue, I dont know how to use it dynamically and multidimensonally...


Because the most important about my array/queue MUST be a global struct.

I tried to explain my problem as soon as I can.
Sorry for my bad english. I hope you guys understand what i want.. Any advice?

[mik2718]

A circular buffer with each element an m-vector ?

http://www.boost.org/doc/libs/1_37_0/libs/circular_buffer/doc/circular_buffer.html

[whocares21]

#include <boost/circular_buffer.hpp>

is this a standard library?

[Cheraphy]

sadly, no it is not.

edit:

What I would do is define a struct containing an array of two deques. I'd define a function for pushing values onto the struct that would make use of deque::swap¹ to shift values into the next row.

1http://www.cplusplus.com/reference/stl/deque/swap/

[whocares21]

thanks buddy but in ur example, i think we cant define deques as global? I mean can we define before the main like " deque<int> first reserve" or sth like that? then allocate?

[mik2718]

You can define any datatype as global.

If you can't use anything outside the STL then you could implement your own circular buffer. This is a pretty easy container to implement.