thread.cpp

#include <iostream>
#include <thread>
#include <vector>

class A
{
public:
    void func()
    {
        auto f = [&](int i) { vec[i] = i; };

        vec.resize(10);

        std::vector<std::thread> ths;
        ths.reserve(10);

        for (int i = 0; i < 10; ++i)
        {
            ths.emplace_back(f, i);
        }

        for (auto & t : ths)
            t.join();
    }

private:
    std::vector<int> vec;
};

int main()
{
    A a;
    a.func();
}