checking if a array is null

Unity Engine
,
1

sorry now its a broken thing

public GameObject[] Enemys = new GameObject[2];


    void Update()
    {
        for (int i = 0; i < Enemys.Length; i++)
        {
            if (Enemys[0] == null)
            {
                Debug.Log("all of them are dead.");
            }
        }
    }
2

You may want to try this approach: asking yourself “Can I???” in smaller and smaller steps.

Imphenzia: How Did I Learn To Make Games:

Also, definitely hit tutorials from Youtube. There are plenty.

Tutorials and example code are great, but keep this in mind to maximize your success and minimize your frustration:

How to do tutorials properly, two (2) simple steps to success:

Step 1. Follow the tutorial and do every single step of the tutorial 100% precisely the way it is shown. Even the slightest deviation (even a single character!) generally ends in disaster. That’s how software engineering works. Every step must be taken, every single letter must be spelled, capitalized, punctuated and spaced (or not spaced) properly, literally NOTHING can be omitted or skipped.
Fortunately this is the easiest part to get right: Be a robot. Don’t make any mistakes.
BE PERFECT IN EVERYTHING YOU DO HERE!!

If you get any errors, learn how to read the error code and fix your error. Google is your friend here. Do NOT continue until you fix your error. Your error will probably be somewhere near the parenthesis numbers (line and character position) in the file. It is almost CERTAINLY your typo causing the error, so look again and fix it.

Step 2. Go back and work through every part of the tutorial again, and this time explain it to your doggie. See how I am doing that in my avatar picture? If you have no dog, explain it to your house plant. If you are unable to explain any part of it, STOP. DO NOT PROCEED. Now go learn how that part works. Read the documentation on the functions involved. Go back to the tutorial and try to figure out WHY they did that. This is the part that takes a LOT of time when you are new. It might take days or weeks to work through a single 5-minute tutorial. Stick with it. You will learn.

Step 2 is the part everybody seems to miss. Without Step 2 you are simply a code-typing monkey and outside of the specific tutorial you did, you will be completely lost. If you want to learn, you MUST do Step 2.

Of course, all this presupposes no errors in the tutorial. For certain tutorial makers (like Unity, Brackeys, Imphenzia, Sebastian Lague) this is usually the case. For some other less-well-known content creators, this is less true. Read the comments on the video: did anyone have issues like you did? If there’s an error, you will NEVER be the first guy to find it.

Beyond that, Step 3, 4, 5 and 6 become easy because you already understand!

Finally, when you have errors, don’t post here… just go fix your errors! Here’s how:

Remember: NOBODY here memorizes error codes. That’s not a thing. The error code is absolutely the least useful part of the error. It serves no purpose at all. Forget the error code. Put it out of your mind.

The complete error message contains everything you need to know to fix the error yourself.

The important parts of the error message are:

  • the description of the error itself (google this; you are NEVER the first one!)
  • the file it occurred in (critical!)
  • the line number and character position (the two numbers in parentheses)
  • also possibly useful is the stack trace (all the lines of text in the lower console window)

Always start with the FIRST error in the console window, as sometimes that error causes or compounds some or all of the subsequent errors. Often the error will be immediately prior to the indicated line, so make sure to check there as well.

Look in the documentation. Every API you attempt to use is probably documented somewhere. Are you using it correctly? Are you spelling it correctly?

All of that information is in the actual error message and you must pay attention to it. Learn how to identify it instantly so you don’t have to stop your progress and fiddle around with the forum.

How to report your problem productively in the Unity3D forums:

http://plbm.com/?p=220

This is the bare minimum of information to report:

  • what you want
  • what you tried
  • what you expected to happen
  • what actually happened, log output, variable values, and especially any errors you see
  • links to documentation you used to cross-check your work (CRITICAL!!!)

The purpose of YOU providing links is to make our job easier, while simultaneously showing us that you actually put effort into the process. If you haven’t put effort into finding the documentation, why should we bother putting effort into replying?

3

im fine with game making its just that i need to find a soulution to seeing if all spaces in an array or list in null or missing

4

Excellent! You’re close. On line 8 you want to use i instead of 0 to dereference enemies, otherwise, you’re only ever looking at the first one.

Generally you would write this for a purpose, and that purpose would dictate the output. Just writing to Debug is fine, but the point of it is you probably want something like end of level to happen.

So rather than me (or someone else) typing it here, go read my first post to you and HIT the tutorials hard.

If you can’t get it from tutorials, you certainly won’t get it from my mad raving scribblings here!

5

It actually isn’t enough to simply reference Enemys if you want to test that “all” the enemies are dead. First make a method AreAllDead() or some such returning a Boolean. Have that method iterate the loop checking Enemys != null and return true if that is the case. You can stop checking if you find a non-null value. And return true if it completes the loop because it would mean they are all null.

6
7

Sometimes it can be easier to reason about a problem if you flip it on its head; instead of trying to solve the problem directly, try to figure out how you could determine if the opposite of it is true or not.

In this case, the statement all enemies are dead is true, if the opposite statement any enemy is alive is false.

So this:

void Update()
{
    if(AreAllEnemiesDead() == true)
    {
        Debug.Log("all of them are dead.");
    }
}

bool AreAllEnemiesDead()
{
    // returns true if every game object in the
    // Enemies array is null, otherwise returns false
}

Can be changed to this:

void Update()
{
    if(IsAnyEnemyAlive() == false)
    {
        Debug.Log("all of them are dead.");
    }
}

bool IsAnyEnemyAlive()
{
    // returns true if any game object in the
    // Enemies array is not null, otherwise returns false
}

Secondly, defining small helper methods can help a lot in making the code easier to read, and helping break the problem into smaller easier to digest pieces.

For example, if the expression in your if statement if(Enemys[0] == null) was extracted into an accurately named helper method, it would read something like if(IsTheFirstEnemyDead()). With this change, we can more easily see that the logic isn’t sound: even if the first enemy is dead, it doesn’t mean that the other enemies are dead as well.

Instead of a helper method that always checks the first enemy, you need a more flexible helper method that can check if any enemy that is passed to it as an argument is dead or alive.

bool IsEnemyAlive(GameObject enemy)
{
    return enemy != null;
}

After these steps the final solution almost writes itself:

bool IsAnyEnemyAlive()
{
    foreach(GameObject enemy in Enemies)
    {
        if(IsEnemyAlive(enemy))
        {
            return true;
        }
    }
 
    return false;
}