Use of unassigned local variable

Hi there!

I'm an artist who is trying to learn a little scripting to test my assets, I'm super new to it. A lot of the code is actually borrowed from elsewhere! I'd really appreciate some help with this problem.

Everything works when played in Unity, but i get the following error when i try to make a build:

(39/44): error CS0165: Use of unassigned local variable 'ray'

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class PlayerMovement : MonoBehaviour {
5.     //flag to check if the user has tapped / clicked.
6.     //Set to true on click. Reset to false on reaching destination
7.     private bool flag = false;
8.     //destination point
9.     private Vector3 endPoint;
10.     //alter this to change the speed of the movement of player / gameobject
11.     public float duration = 50.0f;
12.     private Animator anim;
13.     public Vector3 startPosition;
14.    
15.     void Start(){
16.         startPosition = transform.position;
17.         anim = GetComponent<Animator>();
18.     }
19.    
20.     // Update is called once per frame
21.     void Update () {
22.  
23.         //check if the screen is touched / clicked  
24.         if((Input.touchCount > 0 && Input.GetTouch(0).phase == TouchPhase.Began) || (Input.GetMouseButtonDown(0)))
25.         {
26.             //declare a variable of RaycastHit struct
27.             RaycastHit hit;
28.             //Create a Ray on the tapped / clicked position
29.             Ray ray;
30.             //for unity editor
31.             #if UNITY_EDITOR
32.             ray = Camera.main.ScreenPointToRay(Input.mousePosition);
33.             //for touch device
34.             #elif (UNITY_ANDROID || UNITY_IPHONE || UNITY_WP8)
35.             ray = Camera.main.ScreenPointToRay(Input.GetTouch(0).position);
36.             #endif
37.            
38.             //Check if the ray hits any collider
39.             if(Physics.Raycast(ray, out hit))
40.             {
41.                 //set a flag to indicate to move the gameobject
42.                 flag = true;
43.                 //save the click / tap position
44.                 endPoint = hit.point;
45.                 Debug.Log(endPoint);
46.                 anim.SetFloat("SpeedX", endPoint.x);
47.                 anim.SetFloat("SpeedY", endPoint.y);
48.             }              
49.  
50.         }
51.         //check if the flag for movement is true and the current gameobject position is not same as the clicked / tapped position
52.         if(flag && !Mathf.Approximately(gameObject.transform.position.magnitude, endPoint.magnitude)){ //&& !(V3Equal(transform.position, endPoint))){
53.             //move the gameobject to the desired position
54.             gameObject.transform.position = Vector3.Lerp(gameObject.transform.position, endPoint, 1/(duration*(Vector3.Distance(gameObject.transform.position, endPoint))));
55.         }
56.         //set the movement indicator flag to false if the endPoint and current gameobject position are equal
57.         else if(flag && Mathf.Approximately(gameObject.transform.position.magnitude, endPoint.magnitude)) {
58.             flag = false;
59.             Debug.Log("I am here");
60.         }
61.         {
62.             if(flag && !Mathf.Approximately(gameObject.transform.position.magnitude, endPoint.magnitude)) {
63.                 anim.SetBool("walking", true);
64.             } else if (flag && Mathf.Approximately(gameObject.transform.position.magnitude, endPoint.magnitude)) {
65.                 anim.SetBool("walking", false);
66.                     }
67.        
68.         }
69.  
70.     }
71. }
72.  

 

I believe your conditional compilation means that the compiler can't be sure that ray has been assigned a value before it is used in line 39.

Changing line 29 to

Code (CSharp):

1. Ray ray = null;

should allow it to compile, however you should really change your conditional compilation block to have a default part which also initializes the variable ray, to guard against possible run time errors.

 

Thanks Munchy2007

I tried out your suggestion and got the following error:

CS0037: Cannot convert null to 'UnityEngine.Ray' because it is a value type

As for your other suggestion, I'm still too new to this to understand what you mean I need to spend some more time doing the basic tutorials.

 

A Ray is a struct, and cannot be null.

Your problem is probably that your #if chain does not have a 'default' condition, and though I'm not familiar with all the preprocessor directives, I'd bet that you're building in a situation where none of those are true. I'd restructure it so that the "using mouse" code is the default fallback, rather than being specific to the editor:

Code (csharp):

1.  
2. #if (UNITY_ANDROID || UNITY_IPHONE || UNITY_WP8)
3.             ray = Camera.main.ScreenPointToRay(Input.GetTouch(0).position);
4.             #else
5.             ray = Camera.main.ScreenPointToRay(Input.mousePosition);
6.             #endif
7.  

 

Yay! It will build now

Thanks very much StarManta!

 

if((Input.touchCount > 0 && Input.GetTouch(0).phase == TouchPhase.Began) || (Input.GetMouseButtonDown(0)))
{
//rb.AddForce(transform.up * thrust);
//declare a variable of RaycastHit struct
RaycastHit hit;
//Create a Ray on the tapped / clicked position
Ray ray;

#if (UNITY_ANDROID || UNITY_IPHONE || UNITY_WP8)
ray = Camera.main.ScreenPointToRay(Input.GetTouch(0).position);
#else
ray = Camera.main.ScreenPointToRay(Input.mousePosition);
#endif
//Check if the ray hits any collider
if(Physics.Raycast(ray,out hit))
{
//set a flag to indicate to move the gameobject
flag = true;
//save the click / tap position
endPoint = hit.point;
//as we do not want to change the y axis value based on touch position, reset it to original y axis value
endPoint.y = yAxis;
}

}
//check if the flag for movement is true and the current gameobject position is not same as the clicked / tapped position
if(flag && !Mathf.Approximately(gameObject.transform.position.magnitude, endPoint.magnitude)){ //&& !(V3Equal(transform.position, endPoint))){
//move the gameobject to the desired position
gameObject.transform.position = Vector3.Lerp(gameObject.transform.position, endPoint, 4/(duration*(Vector3.Distance(gameObject.transform.position, endPoint))));
}
//set the movement indicator flag to false if the endPoint and current gameobject position are equal
else if(flag && Mathf.Approximately(gameObject.transform.position.magnitude, endPoint.magnitude)) {
flag = false;
Debug.Log("I am here");
}
}

 

i am getting the same error pls someone help me

error CS0165: Use of unassigned local variable 'ray' : 15th line