内置到集合中的对象的C ++生存期

Question

I have the following code

void my_func() {
    std::vector<std::string> all_strings;
    for (int i = 0 ; i < 10 ; i++) {
        // "loop a"
        all_strings.push_back(std::to_string(i));
    }
    for (const std::string& str : all_strings) {
        // "loop b"
        std::cout << str << std::endl;
    }
}

I created the strings and assigned them into the vector within "loop a". The question is, whether I can access those vector values in "loop b", where the objects created locally and internally in "loop a" are already gone.

In other words, are the strings copied by values into the vector in "loop a"?

Answer 1

Due to the definition of your variable, you are storing std::string objects by value

std::vector<std::string> all_strings;

This means the vector owns copies of the strings, that it will destroy when it falls out of scope.

Answer 2

是的， push_back将复制std::string并将其存储在vector 。