ArgumentNullException: argument cannot be null ?

When I run my game I get this message: "ArgumentNullException: argument cannot be null". Where am I wrong?
This is my script:

Code (CSharp):

1. using UnityEngine;
2.  
3. using System.Collections;
4. using System.Collections.Generic;
5. using UnityEngine.UI;
6. using System.IO;
7.  
8.  
9. public class test : MonoBehaviour {
10.     string[] word = new string[20];
11.     public InputField iField;
12.     private string inputLetter;
13.     public Text showWord;
14.     private int times = 0;
15.    
16.  
17.     private string text;
18.     private string finalWord;
19.  
20.  
21.     void Start(){
22.         text = File.ReadAllText (@"Assets\myWordlist.txt");
23.  
24.     }
25.  
26.     public void OnClick_GO(){
27.         times = times + 1;
28.         inputLetter = iField.text;
29.         word [times] = inputLetter;
30.         Debug.Log(word[times]);
31.         finalWord = string.Join ("", word);
32.         Debug.Log ("Word: " + finalWord);
33.         showWord.text = finalWord;
34.     }
35.  
36.  
37.  
38.     public void OnClick_V(){
39.         if (text.Contains(finalWord))
40.             Debug.Log ("Word exists");
41.         else
42.             Debug.Log ("No");
43.     }
44.  
45.  
46. }

 

Which line?

 

Unfortunately only comes out this message, it does not tell me in which line. After it says "parameter name: value".

 

If you open the Console and click on the error message you'll get a more detailed description.

 

ArgumentNullException: Argument cannot be null.
Parameter name: value
System.String.IndexOf (System.String value) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System/String.cs:1185)
System.String.Contains (System.String value) (at /Users/builduser/buildslave/mono-runtime-and-classlibs/build/mcs/class/corlib/System/String.cs:1429)
prova.OnClick_V () (at Assets/test.cs:44)
UnityEngine.Events.InvokableCall.Invoke (System.Object[] args) (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:149)
UnityEngine.Events.InvokableCallList.Invoke (System.Object[] parameters) (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:626)
UnityEngine.Events.UnityEventBase.Invoke (System.Object[] parameters) (at C:/buildslave/unity/build/Runtime/Export/UnityEvent.cs:766)
UnityEngine.Events.UnityEvent.Invoke () (at C:/buildslave/unity/build/Runtime/Export/UnityEvent_0.cs:54)
UnityEngine.UI.Button.Press () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Button.cs:35)
UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/Button.cs:44)
UnityEngine.EventSystems.ExecuteEvents.Execute (IPointerClickHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:52)
UnityEngine.EventSystems.ExecuteEvents.Execute[IPointerClickHandler] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.EventFunction`1 functor) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:269)
UnityEngine.EventSystems.EventSystem:Update()

 

looks like "finalWord" is null at the point when the OnClick_V function is being called...

 

As @LeftyRighty said, the argument passed to this method is null.

 

Is there a way I can use the variable "final word" in the OnClick_V() function?

 

It looks like "finalWord" is initialized in OnClick_GO but I don't know when that method is invoked in your project.

Try also:

Code (CSharp):

1. if (!string.IsNullOrEmpty(finalWord) && text.Contains(finalWord))
2.     Debug.Log ("Word exists");
3. else
4.     Debug.Log ("No");

 

I tried with this:

but it returns me "No" also if the word is present in the wordlist.

 

He's been doing some sort of word game, functions are called via UI button event calls.

 

Simplest solution is likely to be setting the string as "" in start and just checking if !="" in you button's function. It'll always be something even if you call that function before the other one.

 

@veleno94 Are you sure OnClick_GO gets executed?

Edit:
Please give more details about the project. Also specify when OnClick_GO and OnClick_V are executed.

 

First of all thank you for advices you are giving me.

@ung OnClick_GO is performed correctly. In simple terms, I insert a word in the inputfield and, pressing the button "GO", the word appears on the screen. When I press the "V" button, it should check whether the word is present in the wordlist.

@LeftyRighty I tried your way. It results that the variable "finalWord" remains empty. Then when I call the function OnClick_GO the variable "finalWord" is changed only within the function, and not generally in the script instead.

 

that would suggest you're manipulating a local variable within the function and not the class variable... although i don't see that in the code you posted above