Finding children of a gameobject with a certain tag

Questions & Answers
1

I have walls in my scene, each wall has a set of waypoints in it with the tag waypoint

what i want to know is how to put the child way points into an array

code so far

private GameObject[] waypoints;//<---- need to get the children with tag"waypoint" in here
private GameObject[] walls;

void Start{
walls = GameObject.FindGameObjectsWithTag ("wall");
}

void Update(){
foreach(GameObject wall in walls) {	
	foreach (Transform Child in wall.transform) {
//stuck here, need to get all the children with the tag "waypoint" into the game object array called waypoints
    }
  }
}
2

Try this, modify it to suite your code:

List waypoints=new List();
private GameObject[] walls;

void Update(){
  foreach(GameObject wall in walls) {
    Transform[] childrenOnthisWall = gameObject.GetComponentsInChildren();
    foreach (Transform child in childrenOnthisWall){
      if (child.tag == "waypoint"){
        waypoints.Add(child.gameObject); 
      }
    }
  }
}
3

I think your logic is wrong: if you search for the farthest waypoint each Update, the AI may enter an infinite loop. When needed, you should use FarthestWaypoint(NearestWall()) to find the desired waypoint:

private GameObject[] walls;

void Start{
  walls = GameObject.FindGameObjectsWithTag ("wall");
}

// to find the desired waypoint, use this:
  ...
  GameObject waypoint = FarthestWaypoint(NearestWall());
  ...

// these are the functions:

GameObject NearestWall(){
  float distance = Mathf.Infinity;
  GameObject nearest;
  foreach (GameObject wall in walls){
    // get its squared distance to save a few CPU cycles...
    float dist2 = (wall.transform.position - transform.position).sqrMagnitude;
    if (dist2 < distance){ // if closer than current min distance...
      nearest = wall; // this is the new nearest wall
      distance = dist2;
    }
  }
  return nearest;
}

GameObject FarthestWaypoint(GameObject wall){
  float distance = -1;
  GameObject farthest;
  foreach (Transform child in wall.transform){
    if (child.CompareTag("waypoint")){ // if found a waypoint...
      // get its squared distance to save a few CPU cycles...
      float dist2 = (child.position - transform.position).sqrMagnitude;
      if (dist2 > distance){ // if farther than current max distance...
        farthest = child.gameObject; // this is the new farthest object
        distance = dist2;
      }
    }
  }
  return farthest;
}