Calling functions randomly using a vector - c++

Question

#assume everything needed is included
void Robot::moveRobot()
{
//calls a random directon for robot to move in
//if direction returns false (not able to move in that direction),
//call another random direction up to 4 times, excluding the one(s)
//already called. If they all return false, do not move the robot.
//vecDir = {moveForward(), moveBackward(), moveRight(), moveLeft()}
// = {0,1,2,3} initially
vector<int> vecDir{0,1,2,3}; //vetor indicating direction to move
int num = rand() % vecDir.size();
if(num == vecDir[0])
{
//if not able to move forward, try a different random direction
if(Robot::moveForward() == false)
{
vecDir.erase(num);
//here, vector will be vecDir={1,2,3}
}
}
else if(num == vecDir[1])
{
Robot::moveBackward();
}
else if(num == vecDir[2])
{
Robot::moveRight();
}
else //num == vecDir[3]
{
Robot::moveLeft();
}
}
Hi! I'm trying to randomly call these four functions within the moveRobot() function using a vector whose size is changed depending on if a direction cannot be called. I set moveForward() to the first element, moveBackward() to the second element, etc. If any of the moveXXXX() functions are false, I want to delete that element of the array. Example code shown
Example output:
//before doing anything, vecDir = {0,1,2,3}
int num = rand() % vecDir.size(); //assume num = 1, so it calls moveBackward()
//assume moveBackward() is false, so gets rid of that element
vecDir.erase(num); //new vecDir = {0,2,3};
// vecDir(0) would be moveForward(), vecDir(1) is now moveRight(), vecDir(1) is now moveLeft()
How would I continue this process to exhaust all elements and not move a robot? I know a for loop would be involved, but I cannot think of where to use it. I am also not sure if my thinking is correct by using if else for each element. Any help is appreciated, and I apologize if the question is confusing. I can clear it up if there are any misunderstandings.

Answer 1

Just have a vector of function pointers, rather then numbers.
void Robot::moveRobot() {
// vector of pointers to functions to move
std::vector<bool()> moves{
moveForward(), moveBackward(), moveRight(), moveLeft()
};
// we repeat the process until any moves are available.
while (moves.size() > 0) {
// pick a random move
const int num = rand() % moves.size();
// try to move
if (moves[num]() == true) {
// yay, we moved!
break;
}
// we did not move - remove current option and repeat
moves.erase(moves.begin() + num);
}
}