c++ vector move element to front

To move an element to the front of a C++ vector, you can follow these steps:

  1. Get the element you want to move to the front. You can access the element by using the index or iterator of the vector.

  2. Use the std::move function to move the element. This function takes an rvalue reference and converts it into an xvalue, allowing the element to be efficiently moved rather than copied.

  3. Use the std::rotate function to rotate the range of elements in the vector. The std::rotate function takes three parameters: the first iterator representing the beginning of the range, the iterator representing the element to be moved to the front, and the last iterator representing the end of the range. It rotates the elements in such a way that the specified element becomes the new first element.

  4. After rotating the elements, the desired element will be at the front of the vector.

Here is an example code snippet that demonstrates these steps:

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};

    // Step 1: Get the element to move
    int elementToMove = numbers[3]; // Move the element at index 3

    // Step 2: Move the element
    int& movedElement = numbers[0] = std::move(elementToMove);

    // Step 3: Rotate the elements
    std::rotate(numbers.begin(), numbers.begin() + 1, numbers.end());

    // Step 4: The desired element is now at the front
    std::cout << "Moved element: " << movedElement << std::endl;
    std::cout << "Vector after moving element to front: ";
    for (const auto& number : numbers) {
        std::cout << number << " ";
    }
    std::cout << std::endl;

    return 0;
}

This code snippet moves the element at index 3 to the front of the vector numbers using the steps explained above. The output will be:

Moved element: 4
Vector after moving element to front: 4 1 2 3 5

Please note that this example assumes that the vector contains integers, but the same steps can be applied to vectors of other types as well.