Add examples for ImmutableArray (#8865)

Author: MSDN-WhiteKnight

snippets/csharp/System.Collections.Immutable/ImmutableArray`1/Overview/ImmutableArraySnippets.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Immutable;
+
+static class ImmutableArraySnippets
+{
+    static void ImmutableArrayNumbers()
+    {
+        // <SnippetIterate>
+        // Create an immutable array of numbers
+        ImmutableArray<int> numbers = ImmutableArray.Create(1, 2, 3, 4, -1, -2);
+
+        // Iterate over all items in the array and print them
+        foreach (int n in numbers)
+        {
+            Console.Write(n);
+            Console.Write(' ');
+        }
+        // Output: 1 2 3 4 -1 -2
+        // </SnippetIterate>
+        
+        // <SnippetModify>
+        ImmutableArray<int> numbers2 = numbers.RemoveAt(0).Add(-3);
+        // numbers2 will contain: 2 3 4 -1 -2 -3
+        // </SnippetModify>
+
+        // <SnippetBuilder>
+        // Create immutable array builder
+        ImmutableArray<int>.Builder builder = ImmutableArray.CreateBuilder<int>();
+
+        // Iterate over all items in the original array and add positive elements to the builder
+        for (int i = 0; i < numbers.Length; i++)
+        {
+            if (numbers[i] > 0) builder.Add(numbers[i]);
+        }
+
+        // Create an immutable array from the contents of the builder
+        ImmutableArray<int> numbers3 = builder.ToImmutable();
+        // numbers3 will contain: 1 2 3 4
+        // </SnippetBuilder>
+    }
+
+    public static void Run()
+    {
+        ImmutableArrayNumbers();
+    }
+}
+

snippets/csharp/System.Collections.Immutable/ImmutableArray`1/Overview/ImmutableArraySnippets.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net7.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>

snippets/csharp/System.Collections.Immutable/ImmutableArray`1/Overview/Program.cs

@@ -0,0 +1,10 @@
+using System;
+
+class Program
+{
+    static void Main()
+    {
+        ImmutableArraySnippets.Run();
+    }
+}
+

xml/System.Collections.Immutable/ImmutableArray`1.xml

@@ -107,6 +107,19 @@
 |**Operation**|<xref:System.Collections.Immutable.ImmutableArray%601> Complexity|<xref:System.Collections.Immutable.ImmutableList%601> Complexity|**Comments**|  
 |**Item**|O(1)|O(log n)|Directly index into the underlying array|  
 |**Add()**|O(n)|O(log n)|Requires creating a new array|  
+
+## Examples
+This example shows how to create an immutable array and iterate over elements in it:
+
+:::code language="csharp" source="~/snippets/csharp/System.Collections.Immutable/ImmutableArray`1/Overview/ImmutableArraySnippets.cs" id="SnippetIterate":::
+
+This example shows how to create a new immutable array by adding and removing items from the original array:
+
+:::code language="csharp" source="~/snippets/csharp/System.Collections.Immutable/ImmutableArray`1/Overview/ImmutableArraySnippets.cs" id="SnippetModify":::
+
+This example shows how to create an immutable array using <xref:System.Collections.Immutable.ImmutableArray%601.Builder>:
+
+:::code language="csharp" source="~/snippets/csharp/System.Collections.Immutable/ImmutableArray`1/Overview/ImmutableArraySnippets.cs" id="SnippetBuilder"::: 
   
  ]]></format>
     </remarks>