向量位置上的c++ std:: vector : sum

std::vector<int> intVector;
std::vector<double> doubleVector;
std::vector<std::string> stringVector;

#include <iostream>
#include <vector>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    int sum = 0;

    for (int num : numbers) {
        sum += num;
    }

    std::cout << "Sum of elements: " << sum << std::endl;
    return 0;
}

int sizeBeforeModification = numbers.size();
// 进行一些修改操作
int sizeAfterModification = numbers.size();
if (sizeBeforeModification != sizeAfterModification) {
    std::cout << "Vector size has changed!" << std::endl;
}

if (index >= 0 && index < numbers.size()) {
    int value = numbers[index];
} else {
    std::cout << "Index out of range!" << std::endl;
}