Apply suggestions from code review

Co-authored-by: Bill Wagner <[email protected]>

Author: gewarren

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

@@ -5,7 +5,7 @@ public class Array1Example
 {
     public static void Main()
     {
-        string[] values = { "one", null, "two" };
+        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) ? "" : ", ");

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

@@ -5,7 +5,7 @@ public class Array2Example
 {
     public static void Main()
     {
-        string[] values = { "one", null, "two" };
+        string[] values = [ "one", null, "two" ];
         for (int ctr = 0; ctr <= values.GetUpperBound(0); ctr++)
             Console.Write("{0}{1}",
                           values[ctr] != null ? values[ctr].Trim() : "",

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

@@ -11,7 +11,7 @@ public static void Main()
             if (!string.IsNullOrEmpty(pages.CurrentPage.Title))
             {
                 string title = pages.CurrentPage.Title;
-                Console.WriteLine("Current title: '{0}'", title);
+                Console.WriteLine($"Current title: '{title}'");
             }
         }
     }
@@ -44,7 +44,7 @@ public Page PreviousPage
             {
                 if (_ctr == 0)
                 {
-                    if (_page[0] == null)
+                    if (_page[0] is null)
                         return null;
                     else
                         return _page[0];

snippets/csharp/System/NullReferenceException/Overview/Chain2.cs

@@ -10,7 +10,7 @@ public static void Main()
         if (current != null)
         {
             string title = current.Title;
-            Console.WriteLine("Current title: '{0}'", title);
+            Console.WriteLine($"Current title: '{title}'");
         }
         else
         {

snippets/csharp/System/NullReferenceException/Overview/nullreturn2.cs

@@ -19,7 +19,7 @@ public static void Main()
 
     public class Person
     {
-        public static Person[] AddRange(string[] firstNames)
+        public static Person[] AddRange(params string[] firstNames)
         {
             Person[] p = new Person[firstNames.Length];
             for (int ctr = 0; ctr < firstNames.Length; ctr++)