How do i index system arrays?

Questions & Answers
1

void UpdateCost(){
GameObject towers = GameObject.FindGameObjectsWithTag(“Tower”);
int QuantityOfTowers = 0 ;
for(int i = 0; i<tower.Length;i++){
for(int c = 0; c<towers.Length;c++){
if(tower*.name == towers*
~~~c
.name){
QuantityOfTowers++;
}
}
HowMuchCosts = BackupHowMuchCosts*/this is the array im talking about/ + extraCost**QuantityOfTowers;
QuantityOfTowers = 0;
}
}

So, what i want is to index the system array (not that built in one, the System.Array one) so i can sum with other values, but it is not working. How do i index the arrays?
It would be good if i could convert the array to a builtin array or a generic list. I cannot make the array into a builtin array becouse i need that it has the same starter values of HowMuchCosts, and the builtin array just references and it has the same values of that array in all times, when a value of howmuchcosts changes, it also changes on that builtin array. Please help?

Entire Script:
using UnityEngine;
using System;
using System.Collections;
using System.Collections.Generic;

public class PlantTower : MonoBehaviour {
	public Material StarterMaterial;
	public Material MOMaterial;
	public static PlantTower open;
	public bool guienabled = false;
	public GameObject[] tower;
	public int[] HowMuchCosts;
	public CameraSetter set;
	public bool CanOpen = true;
	public int[] extraCost;
	
	private Array BackupHowMuchCosts;
	
	void Awake(){
		open = this;
		Array.Copy (HowMuchCosts,BackupHowMuchCosts,HowMuchCosts.Length);
	}
	
	void OnMouseDown(){
		if (set.GuialreadyOpened == false&& CanOpen == true) {	
			audio.Play();
			guienabled = true;
			set.GuialreadyOpened = true;
		}
	}

	void OnMouseOver () {
		if(set.GuialreadyOpened == false)
			renderer.material = MOMaterial;
	}

	void OnMouseExit(){
		if(set.GuialreadyOpened == false)
			renderer.material = StarterMaterial;
	}
	
	void UpdateCost(){	
		GameObject[] towers = GameObject.FindGameObjectsWithTag("Tower");
		int QuantityOfTowers = 0 ;
		for(int i = 0; i<tower.Length;i++){
			for(int c = 0; c<towers.Length;c++){
				if(tower*.name ==  towers[c].name){
					QuantityOfTowers++;
				}
			}
			HowMuchCosts* = BackupHowMuchCosts* + extraCost**QuantityOfTowers;
			QuantityOfTowers = 0;
		}
	}
	
	void FixedUpdate(){
		UpdateCost();
	}
	
	void OnGUI () {
		
		if (guienabled == true && CanOpen == true &&set.English == true&&set.guiactive) {
			GUI.Box (new Rect (Screen.width / 2 - 100, Screen.height / 2 - 200, 200, 400), "Choose a Tower");

			int i;
			float y = 180;
			for(i = 0; i<tower.Length;i++){
				
				y -= 30;
				if (GUI.Button (new Rect (Screen.width / 2 - 75, Screen.height / 2 - 10 - y, 150, 20), tower*.name+" ("+HowMuchCosts*+" GC)")) {
					audio.Play();
					if (Motor.Instance.GoldenCoins >= HowMuchCosts*) {
						
						GameObject tow = (GameObject)Instantiate (tower*, transform.position + new Vector3 (0f, 3f, 0f), transform.rotation);
						tow.GetComponent<Tower>().pad = gameObject;
						string str1 = "(Clone)";
						string str2 = tow.name;
						tow.name = str2.Replace(str1,"");
						Motor.Instance.GoldenCoins -= HowMuchCosts*;
						set.GuialreadyOpened = false;
						gameObject.renderer.enabled = false;
						guienabled = false;
						CanOpen = false;
						renderer.material = StarterMaterial;
					}
				}
			}
			if (GUI.Button (new Rect (Screen.width / 2 - 11.5f + 88, Screen.height / 2 - 10 - 190, 23, 20), "X")) {
				audio.Play();
				guienabled = false;
				set.GuialreadyOpened = false;
				renderer.material = StarterMaterial;
			}
		} else if (guienabled == true &&CanOpen == true&& set.English == false&&set.guiactive) {
			GUI.Box (new Rect (Screen.width / 2 - 100, Screen.height / 2 - 200, 200, 400), "Escolha a Torre");
			
			int i;
			float y = 180;
			for(i = 0; i<tower.Length;i++){
				y -= 30;
				Tower towe = tower*.GetComponent<Tower>();
				if (GUI.Button (new Rect (Screen.width / 2 - 75, Screen.height / 2 - 10 - y, 150, 20), towe.NIP+" ("+HowMuchCosts*+" CO)")) {
					audio.Play();
					if (Motor.Instance.GoldenCoins >= HowMuchCosts*) {
						GameObject tow = (GameObject)Instantiate (tower*, transform.position + new Vector3 (0f, 3f, 0f), transform.rotation);
						tow.GetComponent<Tower>().pad = gameObject;
						Motor.Instance.GoldenCoins -= HowMuchCosts*;
						set.GuialreadyOpened = false;
						gameObject.renderer.enabled = false;
						guienabled = false;
						CanOpen = false;
						renderer.material = StarterMaterial;
					}
				}
			}
			if (GUI.Button (new Rect (Screen.width / 2 - 11.5f + 88, Screen.height / 2 - 10 - 190, 23, 20), "X")) {
				audio.Play();
				guienabled = false;
				set.GuialreadyOpened = false;
				renderer.material = StarterMaterial;
			}
		}
	}
}

And im getting this error:

Assets/Scripts/PlantTower.cs(51,43): error CS0021: Cannot apply indexing with to an expression of type `System.Array’*
~~~

2

System.Array is an abstract class, so you should not create an instance of it. You should just initialize it as a new int array and then copy into it:

private int[] BackupHowMuchCosts;

void Awake(){
	BackupHowMuchCosts = new int[HowMuchCosts.Length];
	Array.Copy(HowMuchCosts,BackupHowMuchCosts,HowMuchCosts.Length);
	open = this;
}

Then you can find the value of an index:

BackupHowMuchCosts

Happy Holidays!
Scribe