Add project file and modernize code

snippets/csharp/System/NullReferenceException/Overview/Array1.cs

@@ -1,19 +1,19 @@
-// <Snippet8>
-using System;
+using System;
 
-public class Example
+public class Array1Example
 {
-   public static void Main()
-   {
-      String[] values = { "one", null, "two" };
-      for (int ctr = 0; ctr <= values.GetUpperBound(0); ctr++)
-         Console.Write("{0}{1}", values[ctr].Trim(),
-                       ctr == values.GetUpperBound(0) ? "" : ", ");
-      Console.WriteLine();
-   }
+    public static void Main()
+    {
+        // <Snippet8>
+        string[] values = [ "one", null, "two" ];
+        for (int ctr = 0; ctr <= values.GetUpperBound(0); ctr++)
+            Console.Write("{0}{1}", values[ctr].Trim(),
+                          ctr == values.GetUpperBound(0) ? "" : ", ");
+        Console.WriteLine();
+
+        // The example displays the following output:
+        //    Unhandled Exception:
+        //       System.NullReferenceException: Object reference not set to an instance of an object.
+        // </Snippet8>
+    }
 }
-// The example displays the following output:
-//    Unhandled Exception:
-//       System.NullReferenceException: Object reference not set to an instance of an object.
-//       at Example.Main()
-// </Snippet8>

snippets/csharp/System/NullReferenceException/Overview/Array2.cs

@@ -1,18 +1,19 @@
-// <Snippet9>
-using System;
+using System;
 
-public class Example
+public class Array2Example
 {
-   public static void Main()
-   {
-      String[] values = { "one", null, "two" };
-      for (int ctr = 0; ctr <= values.GetUpperBound(0); ctr++)
-         Console.Write("{0}{1}",
-                       values[ctr] != null ? values[ctr].Trim() : "",
-                       ctr == values.GetUpperBound(0) ? "" : ", ");
-      Console.WriteLine();
-   }
+    public static void Main()
+    {
+        // <Snippet9>
+        string[] values = [ "one", null, "two" ];
+        for (int ctr = 0; ctr <= values.GetUpperBound(0); ctr++)
+            Console.Write("{0}{1}",
+                          values[ctr] != null ? values[ctr].Trim() : "",
+                          ctr == values.GetUpperBound(0) ? "" : ", ");
+        Console.WriteLine();
+
+        // The example displays the following output:
+        //       one, , two
+        // </Snippet9>
+    }
 }
-// The example displays the following output:
-//       one, , two
-// </Snippet9>

snippets/csharp/System/NullReferenceException/Overview/Array3.cs

@@ -1,20 +1,21 @@
-// <Snippet10>
-using System;
+using System;
 
-public class Example
+public class Array3Example
 {
-   public static void Main()
-   {
-       int[] values = null;
-       for (int ctr = 0; ctr <= 9; ctr++)
-          values[ctr] = ctr * 2;
+    public static void Main()
+    {
+        // <Snippet10>
+        int[] values = null;
+        for (int ctr = 0; ctr <= 9; ctr++)
+            values[ctr] = ctr * 2;
 
-       foreach (var value in values)
-          Console.WriteLine(value);
-   }
+        foreach (int value in values)
+            Console.WriteLine(value);
+
+        // The example displays the following output:
+        //    Unhandled Exception:
+        //       System.NullReferenceException: Object reference not set to an instance of an object.
+        //       at Array3Example.Main()
+        // </Snippet10>
+    }
 }
-// The example displays the following output:
-//    Unhandled Exception:
-//       System.NullReferenceException: Object reference not set to an instance of an object.
-//       at Example.Main()
-// </Snippet10>

snippets/csharp/System/NullReferenceException/Overview/Array4.cs

@@ -1,27 +1,28 @@
-// <Snippet11>
-using System;
+using System;
 
-public class Example
+public class Array4Example
 {
-   public static void Main()
-   {
-       int[] values = new int[10];
-       for (int ctr = 0; ctr <= 9; ctr++)
-          values[ctr] = ctr * 2;
+    public static void Main()
+    {
+        // <Snippet11>
+        int[] values = new int[10];
+        for (int ctr = 0; ctr <= 9; ctr++)
+            values[ctr] = ctr * 2;
 
-       foreach (var value in values)
-          Console.WriteLine(value);
-   }
+        foreach (int value in values)
+            Console.WriteLine(value);
+
+        // The example displays the following output:
+        //    0
+        //    2
+        //    4
+        //    6
+        //    8
+        //    10
+        //    12
+        //    14
+        //    16
+        //    18
+        // </Snippet11>
+    }
 }
-// The example displays the following output:
-//    0
-//    2
-//    4
-//    6
-//    8
-//    10
-//    12
-//    14
-//    16
-//    18
-// </Snippet11>

snippets/csharp/System/NullReferenceException/Overview/Chain1.cs

@@ -1,62 +1,72 @@
-// <Snippet6>
-using System;
+using System;
 
-public class Example
+namespace Chain1
 {
-   public static void Main()
-   {
-      var pages = new Pages();
-      if (!String.IsNullOrEmpty(pages.CurrentPage.Title)) {
-         String title = pages.CurrentPage.Title;
-         Console.WriteLine("Current title: '{0}'", title);
-      }
-   }
-}
+    // <Snippet6>
+    public class Chain1Example
+    {
+        public static void Main()
+        {
+            var pages = new Pages();
+            if (!string.IsNullOrEmpty(pages.CurrentPage.Title))
+            {
+                string title = pages.CurrentPage.Title;
+                Console.WriteLine($"Current title: '{title}'");
+            }
+        }
+    }
 
-public class Pages
-{
-   Page[] page = new Page[10];
-   int ctr = 0;
+    public class Pages
+    {
+        readonly Page[] _page = new Page[10];
+        int _ctr = 0;
 
-   public Page CurrentPage
-   {
-      get { return page[ctr]; }
-      set {
-         // Move all the page objects down to accommodate the new one.
-         if (ctr > page.GetUpperBound(0)) {
-            for (int ndx = 1; ndx <= page.GetUpperBound(0); ndx++)
-               page[ndx - 1] = page[ndx];
-         }
-         page[ctr] = value;
-         if (ctr < page.GetUpperBound(0))
-            ctr++;
-      }
-   }
+        public Page CurrentPage
+        {
+            get { return _page[_ctr]; }
+            set
+            {
+                // Move all the page objects down to accommodate the new one.
+                if (_ctr > _page.GetUpperBound(0))
+                {
+                    for (int ndx = 1; ndx <= _page.GetUpperBound(0); ndx++)
+                        _page[ndx - 1] = _page[ndx];
+                }
+                _page[_ctr] = value;
+                if (_ctr < _page.GetUpperBound(0))
+                    _ctr++;
+            }
+        }
 
-   public Page PreviousPage
-   {
-      get {
-         if (ctr == 0) {
-            if (page[0] == null)
-               return null;
-            else
-               return page[0];
-         }
-         else {
-            ctr--;
-            return page[ctr + 1];
-         }
-      }
-   }
-}
+        public Page PreviousPage
+        {
+            get
+            {
+                if (_ctr == 0)
+                {
+                    if (_page[0] is null)
+                        return null;
+                    else
+                        return _page[0];
+                }
+                else
+                {
+                    _ctr--;
+                    return _page[_ctr + 1];
+                }
+            }
+        }
+    }
 
-public class Page
-{
-   public Uri URL;
-   public String Title;
+    public class Page
+    {
+        public Uri URL;
+        public string Title;
+    }
+
+    // The example displays the following output:
+    //    Unhandled Exception:
+    //       System.NullReferenceException: Object reference not set to an instance of an object.
+    //       at Chain1Example.Main()
+    // </Snippet6>
 }
-// The example displays the following output:
-//    Unhandled Exception:
-//       System.NullReferenceException: Object reference not set to an instance of an object.
-//       at Example.Main()
-// </Snippet6>