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Bug If statement continues to execute after it becomes false

Discussion in 'Editor & General Support' started by simonpenia, Jan 9, 2023.

  1. simonpenia


    Oct 25, 2020
    Hello forum, I'm having an issue with an if statement for spawning enemies at random intervals.
    The issue is that after timeToSpawn gets turned into a random number, the if statement continues to detect it as 0.
    Should I use an else statement too?
    If it helps I'm using Unity 2021.3.15f1
    Here is the code:

    Code (csharp):
    1. using UnityEngine;
    3. public class E_Spawner : MonoBehaviour
    4. {
    5.     public GameObject enemy;
    6.     public float timeToSpawn, minSpawnTime, maxSpawnTime;
    8.     // Start is called before the first frame update
    9.     void Start()
    10.     {
    11.         timeToSpawn = 10;
    12.     }
    14.     // Update is called once per frame
    15.     void Update()
    16.     {
    17.         timeToSpawn -= Time.deltaTime;
    18.         if(timeToSpawn <= 0)
    19.         {
    20.             timeToSpawn = Random.Range(minSpawnTime, maxSpawnTime);
    21.             Instantiate(enemy, transform);
    22.         }
    23.     }
    24. }
    Can someone help me fix this?

    Kind regards,
  2. Kurt-Dekker


    Mar 16, 2013
    After line 20, print it out! Also, print out what your min / max values are.

    This is just basic debugging. I'm sure you'll learn something surprising by doing the above, such as how some value isn't what you thought it was, which applies to approximately 100% of all bugs.

    You must find a way to get the information you need in order to reason about what the problem is.

    Once you understand what the problem is, you may begin to reason about a solution to the problem.

    What is often happening in these cases is one of the following:

    - the code you think is executing is not actually executing at all
    - the code is executing far EARLIER or LATER than you think
    - the code is executing far LESS OFTEN than you think
    - the code is executing far MORE OFTEN than you think
    - the code is executing on another GameObject than you think it is
    - you're getting an error or warning and you haven't noticed it in the console window

    To help gain more insight into your problem, I recommend liberally sprinkling
    statements through your code to display information in realtime.

    Doing this should help you answer these types of questions:

    - is this code even running? which parts are running? how often does it run? what order does it run in?
    - what are the values of the variables involved? Are they initialized? Are the values reasonable?
    - are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

    Knowing this information will help you reason about the behavior you are seeing.

    You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as

    If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

    You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

    You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

    You could also just display various important quantities in UI Text elements to watch them change as you play the game.

    If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: or this answer for Android:

    If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

    Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

    Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

    When in doubt, print it out!(tm)

    Note: the
    function is an alias for Debug.Log() provided by the MonoBehaviour class.
  3. simonpenia


    Oct 25, 2020
    This worked. Thanks!