Add project file and modernize code

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

@@ -1,16 +1,16 @@
 // <Snippet8>
 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()
+    {
+        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:

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

@@ -1,17 +1,17 @@
 // <Snippet9>
 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()
+    {
+        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

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

@@ -1,17 +1,17 @@
 // <Snippet10>
 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()
+    {
+        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:

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

@@ -1,17 +1,17 @@
 // <Snippet11>
 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()
+    {
+        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

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

@@ -1,62 +1,71 @@
-// <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: '{0}'", 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] == 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 Example.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>

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

@@ -1,64 +1,71 @@
 // <Snippet7>
 using System;
 
-public class Example
+public class Chain2Example
 {
-   public static void Main()
-   {
-      var pages = new Pages();
-      Page current = pages.CurrentPage;
-      if (current != null) {
-         String title = current.Title;
-         Console.WriteLine("Current title: '{0}'", title);
-      }
-      else {
-         Console.WriteLine("There is no page information in the cache.");
-      }
-   }
+    public static void Main()
+    {
+        var pages = new Pages();
+        Page current = pages.CurrentPage;
+        if (current != null)
+        {
+            string title = current.Title;
+            Console.WriteLine("Current title: '{0}'", title);
+        }
+        else
+        {
+            Console.WriteLine("There is no page information in the cache.");
+        }
+    }
 }
 // The example displays the following output:
 //       There is no page information in the cache.
 // </Snippet7>
 
 public class Pages
 {
-   Page[] page = new Page[10];
-   int ctr = 0;
+    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;
+    public Page PreviousPage
+    {
+        get
+        {
+            if (_ctr == 0)
+            {
+                if (_page[0] == null)
+                    return null;
+                else
+                    return _page[0];
+            }
             else
-               return page[0];
-         }
-         else {
-            ctr--;
-            return page[ctr + 1];
-         }
-      }
-   }
+            {
+                _ctr--;
+                return _page[_ctr + 1];
+            }
+        }
+    }
 }
 
 public class Page
 {
-   public Uri URL;
-   public String Title;
+    public Uri URL;
+    public string Title;
 }

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

@@ -0,0 +1,4 @@
+// Do something
+using System;
+
+Console.WriteLine("Hello World");

snippets/csharp/System/NullReferenceException/Overview/Project.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>

snippets/csharp/System/NullReferenceException/Overview/example1.cs

@@ -1,18 +1,17 @@
 // <Snippet1>
-using System;
 using System.Collections.Generic;
 
-public class Example
+public class UseBeforeAssignExample
 {
-   public static void Main(string[] args)
-   {
-      int value = Int32.Parse(args[0]);
-      List<String> names;
-      if (value > 0)
-         names = new List<String>();
+    public static void Main(string[] args)
+    {
+        int value = int.Parse(args[0]);
+        List<string> names;
+        if (value > 0)
+            names = [];
 
-      names.Add("Major Major Major");
-   }
+        //names.Add("Major Major Major");
+    }
 }
 // Compilation displays a warning like the following:
 //    Example1.cs(10) : warning BC42104: Variable //names// is used before it