GetComponent & Health Question!

[spritesobhan]

I am working an a battle sequence scene for an RPG and so far I have a script for the player and the enemy health, and am trying to call the enemy health variable from the player script.

using UnityEngine;
using System.Collections;

public class Player : MonoBehaviour {

public int playerHealth;
public GameObject enemysprite;

private Enemy enemy;

// Use for calling variables
void Awake () {
enemy = **enemy.**GetComponent ();

}

// Use this for initialization
void Start () {
playerHealth= 100;

}

// Update is called once per frame
private void Update () {
if(Input.GetKeyDown(KeyCode.Q))
{
enemy.enemyHealth = enemy.enemyHealth- 5;
}
}

}

My question is why doesn’t this script work without having to attach the game object to this script?
The script, left exactly the same way without the bold parts, returns an error like this

NullReferenceException: Object reference not set to an instance of an object
Player.Update () (at Assets/Levels/2 - Instance/Player.cs:27)

The reason I am worried about this right now is because if later on if I have 500 enemies, I don’t want to have to attach each of their gameObjects to my main player to subtract their health.

[spritesobhan]

public Text healthbar;

void Update () {
healthbar.text = seikoHealth;
}
}

another question is why do i get a “cannot implicitly convert int type to string” error here

[Suddoha]

@spritesobhan

I am working an a battle sequence scene for an RPG and so far I have a script for the player and the enemy health, and am trying to call the enemy health variable from the player script.

My question is why doesn’t this script work without having to attach the game object to this script?
The script, left exactly the same way without the bold parts, returns an error like this

NullReferenceException: Object reference not set to an instance of an object
Player.Update () (at Assets/Levels/2 - Instance/Player.cs:27)

The reason I am worried about this right now is because if later on if I have 500 enemies, I don’t want to have to attach each of their gameObjects to my main player to subtract their health.

I assume the bold part in Awake would be ‘enemysprite:GetComponent…’ instead of just ‘enemy’.

Any component in your scene must belong to a GameObject, and GetComponent tries to get an instance from a GameObject.

If you do not specify a GameObject, such as

GetComponent<TComponent>()

that will end up being the same as
this.GetComponent<TComponent>() where ‘this’ refers to the behaviour itself and is the same as

gameObject.GetComponent<TComponent>()
// or
this.gameObject.GetComponent<TComponent>()

You’ll always get the same result, as the GameObject in this case will always be the one that your script is being attached to.

But your Enemy script is on a different GameObject, so you need to tell the script on which one you want to call the GetComponent method.

You do not necessarily need to link and cache them at startup. There are other techniques that can be used to get a reference to the enemies once you need them. But that depends on your specific needs.

[Suddoha]

@spritesobhan

another question is why do i get a “cannot implicitly convert int type to string” error here

You should call ‘ToString()’ on your integer variable.

healthbar.text = seikoHealth.ToString();

[spritesobhan]

hmm since I don’t have 500 enemies right now I guess I’ll just use getcomponent for now

and thanks, i’ll try the ToString once unity is finished updating