Working with Accessing Deques

The provided code snippet demonstrates the use of a `deque` (double-ended queue) in C++. Let's break down the functionality step by step: 1. **Include Directives and Namespace**: ```cpp #include <iostream> #include <deque> using namespace std; ``` The code starts by including the necessary headers for input/output streaming (`<iostream>`) and for using the deque container (`<deque>`). The `using namespace std;` statement allows us to use standard library features without needing to prefix them with `std::`. 2. **Main Function**: ```cpp int main() { ``` The program's execution begins in the main function. 3. **Creating a Deque**: ```cpp deque<int> numbers(5, 0); ``` Here, a `deque` named `numbers` is created with an initial size of 5, where all elements are initialized to 0. 4. **Iterating with an Iterator**: ```cpp deque<int>::iterator it; for(it = (); it != (); it++) { cout << "Enter a number: "; cin >> *it; } ``` An iterator `it` is declared to traverse the `deque`. In this loop, the program prompts the user to enter numbers, which are stored in the `deque` at the corresponding positions. 5. **Displaying the Contents**: ```cpp for (int i = 0; i < 5; i++) { cout << numbers[i] << "t" << endl; } ``` This loop prints each element of the `deque` followed by a tab and a newline. 6. **Accessing Front and Back Values**: ```cpp cout << "The front value is " << () << endl; cout << "The back value is " << () << endl; ``` The front and back elements of the `deque` are printed using the `front()` and `back()` member functions. 7. **Getting the Size**: ```cpp cout << "There are " << () << " on the deque" << endl; ``` The total number of elements in the `deque` is displayed using the `size()` method. 8. **Removing Elements**: ```cpp _front(); _back(); ``` The `pop_front()` and `pop_back()` functions remove the first and last elements respectively. 9. **Displaying the New Size**: ```cpp cout << "After the pop_front and pop_back functions, there are " << () << " on the deque" << endl; ``` Finally, the new size of the `deque` is printed after the removals. This code provides a simple interactive demonstration of how to use a `deque` in C++, including adding, accessing, and removing elements.