Do I always need to have these default lines of code?

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


These lines of code are created by default when we create new script, but do we always need it? All 3 of it?

 

No, they are just some commonly used namespaces, use them when you need them, they aren't required.

For example, the IEnumerator that is used in Unity Coroutines is available at System.Collections namespace, so it is needed.

And also, the List<T> and IEnumerator<T>, ... all are available at System.Collections.Generic.

And most importantly, the Unity components and classes are available at UnityEngine namespace, for example, the MonoBehaviour class is available at UnityEngine.

They aren't required, they are just most commonly used.

Thanks.

 

sometimes yes sometimes no.

They are including namespaces for you to use in your Scope.
UnityEngine is required for pretty much all basic Unity api stuff, including MonoBahviours
System.Collections is included by default because coroutines require the IEnumerator type that is in it.
System.Collections.Generic is used by almost all generic collection types, List<T>, Stack<T>, Dictionary<K, V> etc.

 

Alright, is there a page where I can see which namespace is required for which components?

 

You can find each at their own documentation:

• UnityEngine: Unity - Scripting API
• System.Collections: System.Collections Namespace
• System.Collections.Generic: System.Collections.Generic Namespace

Thanks.

 

Exactly what I needed, thanks!

 

You never truly need any of them. You can write complete programs without ever having them in your code. That said if you remove them you'll need to refer to the namespace every single time you wish to use something contained in it.

With using:

Code (csharp):

1. using UnityEngine;
2.  
3. public class Foo : MonoBehaviour
4. {
5.     public void Start()
6.     {
7.         Debug.Log("Hello world!");
8.     }
9. }

Without using:

Code (csharp):

1. public class Foo : UnityEngine.MonoBehaviour
2. {
3.     public void Start()
4.     {
5.         UnityEngine.Debug.Log("Hello world!");
6.     }
7. }

You can safely remove the ones you're not using but there are no real advantages to doing so other than to keep your code clean, reduce the likelyhood that you run into a name clash (two namespaces using the same name for part of their content), and to reduce the contents of the auto completion dialog.

Worst case if you remove one that you needed you'll just get errors from the compiler about how it can't find the class, enum, etc that you were referring to and asking if you forgot to include the namespace.

 

No advantages? No improvement in performance or memory?

 

There are no advantages, they are just the look of the code.

If you want clean code, add use statements at top of script.

 

also could you tell me how to embed those lines of like you did, in here, in the forums, I'm new.

 

Alright, thank you.

 

alright, thank you for your time.