programs using vectors in c++

#include <iostream>
#include <vector>

int main() {
    std::vector<int> numbers; // Declare a vector of integers named 'numbers'

    // Add elements to the vector using push_back()
    numbers.push_back(10);
    numbers.push_back(20);
    numbers.push_back(30);

    // Access and print elements using []
    std::cout << "Elements in the vector: ";
    for (size_t i = 0; i < numbers.size(); ++i) {
        std::cout << numbers[i] << " ";
    }
    std::cout << "\n";

    // Modify elements in the vector
    numbers[1] = 50;

    // Iterate through the vector using iterators
    std::cout << "Modified elements using iterators: ";
    for (std::vector<int>::iterator it = numbers.begin(); it != numbers.end(); ++it) {
        std::cout << *it << " ";
    }
    std::cout << "\n";

    // Erase an element from the vector
    numbers.erase(numbers.begin() + 2);

    // Display the final elements in the vector
    std::cout << "Final elements in the vector: ";
    for (const auto& num : numbers) {
        std::cout << num << " ";
    }
    std::cout << "\n";

    return 0;
}

Explanation:

• #include <iostream> and #include <vector>: Includes necessary libraries for input/output operations and vectors.
• std::vector<int> numbers;: Declares a vector named numbers that holds integers.
• numbers.push_back(10);, numbers.push_back(20);, numbers.push_back(30);: Adds elements (10, 20, 30) to the vector using push_back() method.
• for (size_t i = 0; i < numbers.size(); ++i) { std::cout << numbers[i] << " "; }: Iterates through the vector using indices and prints each element.
• numbers[1] = 50;: Modifies the second element of the vector (index 1) and assigns it the value 50.
• for (std::vector<int>::iterator it = numbers.begin(); it != numbers.end(); ++it) { std::cout << *it << " "; }: Iterates through the vector using iterators and prints each element.
• numbers.erase(numbers.begin() + 2);: Erases the third element from the vector.
• for (const auto& num : numbers) { std::cout << num << " "; }: Iterates through the vector using a range-based for loop and prints each element.