" The name "FirstObject" doesn't exist in the current context " ERROR [SOLVED]

I have three objects, and I want the first one to appear on the screen at the begining of the game.
Then, when I click the mouse, I want the first one to dissapear and make the second one appear. On the next click, the second one to dissapear and the third to appear and next the same but dissapearing the third and appearing the first again. Again and again.
The problem is that when I call the function Destroy(MyObject) it doesn't recognize the object.
I create a variable called "condition" that I use to control when I want to create the first object, because as it is inside the update () it would create objects forever.

Code (CSharp):

1. //Code with errors
2. public GameObject[] myGameObject;
3.     private int condition=0;
4.    
5.     void Update () {
6.         if (condition == 0) {
7.             GameObject FirstObject = (GameObject)Instantiate (myGameObject [0], new Vector3 (0, 0, -4), Quaternion.identity);
8.             condition =1;
9.         }
10.         if (Input.GetMouseButtonDown (0)) {
11.             Destroy (FirstObject);
12.             //Now I would create the next object
13.             //GameObject SecondObject = (GameObject)Instantiate (myGameObject [1], new Vector3 (0, 0, -4), Quaternion.identity);
14.         }
15.     }

As you can see the three objects are inside an array of objects.
What I don't undestand is that if I create the object inside the if function of the click it doesn't give me the error, but I need it outside so it doesn't really matter.

Code (CSharp):

1. //Code without errors
2. public GameObject[] myGameObject;
3.     private int condition=0;
4.    
5.     void Update () {
6.      
7.         if (Input.GetMouseButtonDown (0)) {
8.              GameObject FirstObject = (GameObject)Instantiate (myGameObject [0], new Vector3 (0, 0, -4), Quaternion.identity);
9.             Destroy (FirstObject);
10.  
11.         }
12.     }

 

Because your GameObject FirstObject is inside the if block, it is local to this block and not visible to any code outside of it. Make it a member variable of the class instead, because you want to keep it from frame to frame as well.

 

further reading on "scope": https://en.wikipedia.org/wiki/Scope_(computer_science)

 

As what steego said, but with an example just in case.

Spoiler: Click for code

Code (CSharp):

1.     public GameObject[] myGameObject;
2.     private int condition=0;
3.     GameObject someObject;
4.  
5.     void Update () {
6.         if (condition == 0) {
7.             someObject = (GameObject)Instantiate (myGameObject [0], new Vector3 (0, 0, -4), Quaternion.identity);
8.             condition =1;
9.         }
10.         if (Input.GetMouseButtonDown (0)) {
11.             Destroy (someObject);
12.             someObject = (GameObject)Instantiate (myGameObject [1], new Vector3 (0, 0, -4), Quaternion.identity);
13.         }
14.     }

 

Thank you very much for your help guys!