iterate vector from end to begin

To iterate over a vector in C++ from end to beginning, you can use a reverse iterator. Here are the steps to do this:

  1. Declare a vector of the desired type. For example, std::vector<int> myVector;.

  2. Add elements to the vector using the push_back() function. For example, myVector.push_back(10);.

  3. Use the rbegin() and rend() functions of the vector to obtain reverse iterators that point to the last element and one past the first element, respectively. For example, auto it = myVector.rbegin();.

  4. Create a loop using the reverse iterator. The loop should iterate from the last element to the first element. For example, for (; it != myVector.rend(); ++it).

  5. Access the value of the current element using the dereference operator . For example, int value = it;.

  6. Perform any desired operations with the element's value inside the loop.

  7. Continue the loop until the iterator reaches myVector.rend(), which represents one position before the first element.

Here is an example of iterating over a vector from end to beginning:

#include <iostream>
#include <vector>

int main() {
    std::vector<int> myVector;
    myVector.push_back(10);
    myVector.push_back(20);
    myVector.push_back(30);

    for (auto it = myVector.rbegin(); it != myVector.rend(); ++it) {
        int value = *it;
        std::cout << value << " ";
    }

    return 0;
}

Output:

30 20 10