Cs1525 tell me whote is error

Code (csharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class NewBehaviourScript : MonoBehaviour {
5.  
6.     // Use this for initialization
7.     void Start ()
8.     {
9.  public static class IListExtensions {
10.  
11.    public static void Shuffle<T>(this IList<T> ts) {
12.       var count = ts.Count;
13.       var last = count - 1;
14.      for (var i = 0; i < last; ++i) {
15.          var r = UnityEngine.Random.Range(i, count);
16.          var tmp = ts[i];
17.          ts[i] = ts[r];
18.          ts[r] = tmp;
19.  
20.      }
21.  
22.    }
23. }
24. }
25. }

 

You have a class inside a class. These should be separate classes.

Code (csharp):

1.  
2.     using UnityEngine;
3.     using System.Collections;
4.      
5.     public class NewBehaviourScript : MonoBehaviour {
6.      
7.         // Use this for initialization
8.         void Start ()
9.         {
10.      
11.          }
12.     }
13.  
14. public static class IListExtensions {
15.      
16.        public static void Shuffle<T>(this IList<T> ts) {
17.           var count = ts.Count;
18.           var last = count - 1;
19.          for (var i = 0; i < last; ++i) {
20.              var r = UnityEngine.Random.Range(i, count);
21.              var tmp = ts[i];
22.              ts[i] = ts[r];
23.              ts[r] = tmp;
24.      
25.          }
26.      
27.        }
28. }
29.  

 

Believe it or not, classes can legally be nested within the namespaces of other classes:
http://msdn.microsoft.com/en-gb/library/ms173120.aspx

This compilation error is occurring because the OP has attempted to place a class within a method ("Start").

In this particular scenario that class should really reside within its own .cs file.

 

I did forget to mention that. I am sure they did not want nested classes as that intention would not be valid.