[Boost-users] [circular_buffer] About overwriting elements

Subject: [Boost-users] [circular_buffer] About overwriting elements
From: Daniele Barzotti (daniele.barzotti_at_[hidden])
Date: 2010-04-16 09:31:31

Hi,
in the introductory example I see this:

  int a = cb[0];  // a == 1
  int b = cb[1];  // b == 2
  int c = cb[2];  // c == 3

  // The buffer is full now, pushing subsequent
  // elements will overwrite the front-most elements.

  cb.push_back(4);  // Overwrite 1 with 4.
  cb.push_back(5);  // Overwrite 2 with 5.

  // The buffer now contains 3, 4 and 5.

  a = cb[0];  // a == 3
  b = cb[1];  // b == 4
  c = cb[2];  // c == 5

and I would ask why the 4 and 5 are in the 2nd and 3th position instead
of 1st and 2nd respectively.

I thought that it worked in the following way:

 1  2  3                       1  2  3                      1  2  3
[A][B][C]  -> push_back(D) -> [D][B][C] -> push_back(E) -> [D][E][C]

I need a circular buffer for buffering network data and I need that the
old data is replaced but doesn't change its position..

Thanks,
Daniele.