Here is a simple example to introduce the class circular_buffer.

For all examples, we need this include:

#include <boost/circular_buffer.hpp>

This example shows contruction, inserting elements, overwriting and popping.

// Create a circular buffer with a capacity for 3 integers.
boost::circular_buffer<int> cb(3);

// Insert three elements into the buffer.
cb.push_back(1);
cb.push_back(2);
cb.push_back(3);

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

// The buffer is full now, so 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

// Elements can be popped from either the front or the back.
cb.pop_back();  // 5 is removed.
cb.pop_front(); // 3 is removed.

// Leaving only one element with value = 4.
int d = cb[0];  // d == 4

You can see the full example code at circular_buffer_example.cpp.

The full annotated description is in the C++ Reference section.