I have three std::string vectors. 2 of those vectors contain different strings, and the third vector is just to "point" to one of those vectors.

For example

const std::vector<std::string> vec1{ "dynamic", "squid", "s" }
const std::vector<std::string> vec2{ "static", "squid" };

std::vector<std::string> vec = vec1;

This is how I'm using it:

void thread1()
{
  for (int a = 0; a < vec.size(); ++a)
    std::cout << vec[a] << '\n';
}

void thread2()
{
  if (switchSquidType)
  {
    if (vec == vec1)
      vec = vec2;
    else
      vec = vec1;
  }
}

So there are two threads, one to display the information, and one to modify it.

However I found that when I'm drawing vec, it sometimes switches to the other vector mid-draw! That results in an array out of bounds error since vec1 and vec2 have different sizes.

I'm thinking of switching to using char** so I can use std::atomic.

I already tried std::mutex but that didn't work:

std::mutex m;

void thread1()
{
  m.lock();

  for (int a = 0; a < vec.size(); ++a)
    std::cout << vec[a] << '\n';

  m.unlock();
}

void thread2()
{
  if (switchSquidType)
  {
    if (vec == vec1)
      vec = vec2;
    else
      vec = vec1;
  }
}

Same result with std::lock_gaurd.

I linked the repl so you can see what I'm talking about. If you hold down ENTER, you'll see the problem.

So how should I approach this problem? And I doing something wrong with std::mutex? Should I switch to std::atomic<char**>? Or should I completely redesign my project?

I summon the C/C++ people to aid me with my quest (please?):

Any help would be greatly appreciated!