Added snippets for element access operator (#559)

Author: pkulikov

snippets/csharp/language-reference/operators/IndexOperatorExamples.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Collections.Generic;
+
+namespace operators
+{
+    public static class IndexOperatorExamples
+    {
+        public static void Examples()
+        {
+            Arrays();
+            Indexers();
+        }
+
+        private static void Arrays()
+        {
+            // <SnippetArrays>
+            int[] fib = new int[10];
+            fib[0] = fib[1] = 1;
+            for (int i = 2; i < fib.Length; i++)
+            {
+                fib[i] = fib[i - 1] + fib[i - 2];
+            }
+            Console.WriteLine(fib[fib.Length - 1]);  // output: 55
+
+            double[,] matrix = new double[2,2];
+            matrix[0,0] = 1.0;
+            matrix[0,1] = 2.0;
+            matrix[1,0] = matrix[1,1] = 3.0;
+            var determinant = matrix[0,0] * matrix[1,1] - matrix[1,0] * matrix[0,1];
+            Console.WriteLine(determinant);  // output: -3
+            // </SnippetArrays>
+        }
+
+        private static void Indexers()
+        {
+            // <SnippetIndexers>
+            var dict = new Dictionary<string, double>();
+            dict["one"] = 1;
+            dict["pi"] = Math.PI;
+            Console.WriteLine(dict["one"] + dict["pi"]);
+            // </SnippetIndexers>
+        }
+    }
+}

snippets/csharp/language-reference/operators/Program.cs

@@ -49,6 +49,10 @@ static void Main(string[] args)
             Console.WriteLine("======= >, <, >=, and <= operator examples =====");
             GreaterAndLessOperatorsExamples.Examples();
             Console.WriteLine();
+
+            Console.WriteLine("============== [] operator examples ============");
+            IndexOperatorExamples.Examples();
+            Console.WriteLine();
         }
     }
 }