C# adding items to an already created Array

Question

Hello Unity Community,

I am having a really hard time trying to create a piece of code that would add objects that I would select into an array. I was doing some research and it said that I would only be able to do the array.Add or array.Push in java. Which sucks because our project is in C#, is there any alternative that I could possible look into for this problem Thanks, Nolan Encarnacion

using UnityEngine; using System.Collections;

public class SelectionManager : MonoBehaviour { public RaycastHit hit; public Ray ray; public GameObject[] selection; // Use this for initialization

 // Update is called once per frame
 void Update () 
 {
     if ( Input.GetMouseButtonDown(0) )
     {
       ray = Camera.main.ScreenPointToRay (Input.mousePosition);
       if (Physics.Raycast (ray, out hit, 100))
       {
         addtoArray(hit.collider.gameObject);
         Debug.Log(selection);
          //Debug.Log(hit.collider.gameObject.name);
       }
    }

 }
 void addtoArray(gameObject obj)
 {
     selection.Add(obj);
 }

}

Answer 1

Best Answer

Answer by Mike 3 · Apr 07, 2011 at 11:21 PM

You generally want to use List for this kind of thing

Add this to the top of the file:

using System.Collections.Generic;

then this instead of your array:

List<GameObject> selection;

Add should work fine then

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Nolan Encarnacion · Apr 09, 2011 at 02:55 PM 0

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Thank you for your response it was very helpful!

Answer 2

Best Answer

Answer by Peter G · Apr 07, 2011 at 11:23 PM

No, you have to recreate the array with its new member. You may as well make it a generic method:

using System.Collections.Generic;

public static class Extensions {

 public static T[] AddItemToArray &lt;T&gt; (this T[] original, T itemToAdd) {

      T[] finalArray = new T[ original.Length + 1 ];
      for(int i = 0; i &lt; original.Length; i ++ ) {
           finalArray[i] = original[i];
      }

      finalArray[finalArray.Length - 1] = itemToAdd;

      return finalArray;
 }

So as you can see, it isn't very easy to resize arrays.

Or, as Mike said right before I posted, you should probably just use a List. It will handle this for you.

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Nolan Encarnacion · Apr 09, 2011 at 02:56 PM 0

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yeah I think I'm just going to use a list. $$anonymous$$UCH easier haha! Thank you though for your response. It is much appreciated.

Answer 3

Answer by V-Jankaitis · Jun 27, 2018 at 02:06 PM

 T[] AddtoArray<T>(T[] Org, T New_Value)
         {
             T[] New = new T[Org.Length + 1]; 
             Org.CopyTo(New, 0);
             New[Org.Length] = New_Value;
             return New;
         }

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ativtrade · Aug 17, 2021 at 06:15 PM 0

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Did you mean:

New[New.Length] = New_Value;

in line 5?

Bunny83 ativtrade · Aug 17, 2021 at 08:03 PM 0

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No, he didn't. The max valid index is always "Length-1". Since the new length is actually the old length +1 he can simply use the old length as index into the new array.

Example

 // length of array: 4
 // index  0   1   2   3
 // value  A   B   C   D
 
 // new array length: 4+1 == 5
 // index  0   1   2   3   4
 // value  A   B   C   D  New

ativtrade Bunny83 · Aug 17, 2021 at 08:56 PM 0

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Hmm.. effectively recycling Org.Length instead of writing New.Length-1 I think I get it. Thanks for the explanation.

Answer 4

If anyone needed the same script but for models with multiple materials, here you go.

edit: Made fadePerSecond serialized for others who will be using the script in their own way.

 using System.Collections.Generic;
 using UnityEngine;
 
 public class FadeAlpha : MonoBehaviour
 {
     [SerializeField] private float fadePerSecond = 0;
     
     [SerializeField] private List<Material> materials = new List<Material>();
 
     [SerializeField] private bool moreThanOneMat = false;
 
  
     void Start()
     {
         // Locating Materials
         if (GetComponent<MeshRenderer>().materials.Length > 1)
         {
             moreThanOneMat = true;
 
             foreach (Material m in GetComponent<MeshRenderer>().materials)
             {
                 materials.Add(m);
             }
         }
     }
 
     void Update() 
     {
         if (moreThanOneMat == true)
         {
             DropAlphaForAll();
         }
         else
         {
             var material = GetComponent<MeshRenderer>().material;
             var color = material.color;
 
             if (color.a > 0)
             {
                 material.color = new Color(color.r, color.g, color.b, color.a - (fadePerSecond * Time.deltaTime));
             }
             if (color.a < 0)
             {
                 material.color = new Color(color.r, color.g, color.b, 0);
             }
         }
     }
 
     void DropAlphaForAll()
     {
         if (GetComponent<MeshRenderer>().materials.Length > 1)
         {
             foreach (Material mats in materials)
             {
                 if (mats.color.a > 0)
                 {
                     mats.color = new Color(mats.color.r, mats.color.g, mats.color.b, mats.color.a - (fadePerSecond * Time.deltaTime));
                 }
                 if (mats.color.a < 0)
                 {
                     mats.color = new Color(mats.color.r, mats.color.g, mats.color.b, 0);
                 }
             }
         }
     }
 }

C# adding items to an already created Array

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