Why is the std::vector not giving any outputs in c++ - c++

Question

I don't understand why but the std::vector is not giving anything after i put a class pointer in the array.
// runs at start
void States::AssignState(GameState* state) {
_nextVacentState++;
_states.push_back(state);
}
// executes in a loop
void States::ExecuteCurrentState() {
// protection incase there is nothing in the array or the current state is not grater than the size of the array (not the problem after i nerrowed the problem down)
if (_nextVacentState == 0) std::cout << "Error: There is no states, setup some states then try again" << std::endl; return; // there is no states
if (_currentState >= _states.size() - 1) std::cout << "Error: Current State is grater than all possable states" << std::endl; return;
// The program just freezes at this and i can figure out why
_states[0]->tick();
std::printf("S");
}

Answer 1

This is one of the reasons I'd suggest getting in the habit of using curly braces for all if statements, even ones that live on a single line.
A problem line:
if (_nextVacentState == 0) std::cout << "Error: There is no states, setup some states then try again" << std::endl; return;
Let's add some newlines to make it clearer what's happening
if (_nextVacentState == 0)
std::cout << "Error: There is no states, setup some states then try again" << std::endl;
return;
That return statement is getting executed unconditionally, because only the first statement after if(_nextVacentState==0) is actually part of the if. So the compiler executes it as if it had been written like this:
if (_nextVacentState == 0)
{
std::cout << "Error: There is no states, setup some states then try again" << std::endl;
}
return;
But, what you want needs to be written like this instead:
if (_nextVacentState == 0)
{
std::cout << "Error: There is no states, setup some states then try again" << std::endl;
return;
}
You have same problem in the next if check for _currentState, as well.