试图从变量中减去 1，但它减去了 3。C# Unity

Question

I'm trying to reduce an enemy's health by 1 when space is pressed, but when space is pressed, the value is decreased by 3. When the program first runs the variable enemyHealth has a value of 4:

After space is pressed the variable returns as 1. If space is sequentially pressed the value keeps decreasing by 3:

Moving the code that subtracts from enemyHealth to void start yields the same result.

The line of code that subtracts from the enemy's health is running 3 times, which is causing the problem. I, however, have no idea why it's running 3 times.

Player.cs:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Player : MonoBehaviour
{
    private GameObject enemy;
    private Enemy enemyScript;

    // Start is called before the first frame update
    void Start()
    {
        enemy = GameObject.Find("Battle_Dummy");
        enemyScript = enemy.GetComponent<Enemy>();
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            enemyScript.enemyHealth--;
        }
    }
}

Enemy.cs:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Enemy : MonoBehaviour
{
    public int enemyHealth = 4;
    // Start is called before the first frame update
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {

    }
}

Answer 1

Please check if you attached the behaviour multiple times.

Usually Input.GetKeyDown(KeyCode.Space) should fire only once and only fire after you released it again. You can try to do somtething like this to remember it fired and reset it manually (although this should not be needed according to the documentation):

public class Player : MonoBehaviour
{
    private GameObject enemy;
    private Enemy enemyScript;
    private bool handledSpaceBar;

    // Start is called before the first frame update
    void Start()
    {
        enemy = GameObject.Find("Battle_Dummy");
        enemyScript = enemy.GetComponent<Enemy>();
    }

    // Update is called once per frame
    void Update()
    {
        if (!handledSpaceBar && Input.GetKeyDown(KeyCode.Space))
        {
            enemyScript.enemyHealth--;
            handledSpaceBar = true;
        }
        if (handledSpaceBar && Input.GetKeyUp(KeyCode.Space))
        {
            handledSpaceBar = false;
        }
    }
}

---

See

• https://docs.unity3d.com/ScriptReference/Input.GetKeyUp.html
• https://docs.unity3d.com/ScriptReference/Input.GetKeyDown.html