c++ Vector, what happens whenever it expands/reallocate on stack?

Question

I\'m new to C++ and I\'m using the vector class on my project. I found it quite useful because I can have an array that automatically reallocates whenever it is necessary (

Answer 1

If you make some growing vector, from empty, to some size, will be using doubling strategy, and most of the time reallocation, in this example using integer from 1 to 10000, and clang (std=2a -O3) will get this, this is just for fun, showing the importance of using reserve. vector::begin() point to beginning of actual array, and vector::capacity show actual capacity. In the other hand, iterator invalidated is showed.

std::vector my_vec;
auto it=my_vec.begin();
for (int i=0;i<10000;++i) {
    auto cap=my_vec.capacity();
    my_vec.push_back(i);
    if(it!=my_vec.begin()) {
        std::cout<<"it!=my_vec.begin() :";
        it=my_vec.begin();
    }
    if(cap!=my_vec.capacity())std::cout<

This produce the following result:

it!=my_vec.begin() :1
it!=my_vec.begin() :2
it!=my_vec.begin() :4
it!=my_vec.begin() :8
it!=my_vec.begin() :16
it!=my_vec.begin() :32
it!=my_vec.begin() :64
it!=my_vec.begin() :128
it!=my_vec.begin() :256
it!=my_vec.begin() :512
it!=my_vec.begin() :1024
it!=my_vec.begin() :2048
it!=my_vec.begin() :4096
it!=my_vec.begin() :8192
it!=my_vec.begin() :16384