Added foreach keyword snippets (#78)

Author: pkulikov

snippets/csharp/keywords/GenericWhereConstraints.cs

@@ -144,12 +144,15 @@ class Test<T, U>
     { }
     // </Snippet12>
 
-    // <Snippet13>
-    public class List<T>
+    namespace ListExample
     {
-        public void Add<U>(List<U> items) where U : T {/*...*/}
+        // <Snippet13>
+        public class List<T>
+        {
+            public void Add<U>(List<U> items) where U : T {/*...*/}
+        }
+        // </Snippet13>
     }
-    // </Snippet13>
 
     // <Snippet14>
     //Type parameter V is used as a type constraint.

snippets/csharp/keywords/IterationKeywordsExamples.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Generic;
+
+namespace keywords
+{
+    public static class IterationKeywordsExamples
+    {
+        public static void Examples()
+        {
+            ForeachWithIEnumerable();
+            ForeachWithSpan();
+        }
+
+        private static void ForeachWithIEnumerable()
+        {
+            // <Snippet1>
+            var fibNumbers = new List<int> { 0, 1, 1, 2, 3, 5, 8, 13 };
+            int count = 0;
+            foreach (int element in fibNumbers)
+            {
+                count++;
+                Console.WriteLine($"Element #{count}: {element}");
+            }
+            Console.WriteLine($"Number of elements: {count}");
+            // </Snippet1>
+        }
+
+        private static void ForeachWithSpan()
+        {
+            // <Snippet2>
+            Span<int> numbers = new int[] { 3, 14, 15, 92, 6 };
+            foreach (int number in numbers)
+            {
+                Console.Write($"{number} ");
+            }
+            Console.WriteLine();
+            // </Snippet2>
+        }
+    }
+}

snippets/csharp/keywords/Program.cs

@@ -12,6 +12,8 @@ static void Main(string[] args)
             GenericWhereConstraints.Examples();
             Console.WriteLine("=================    Fixed Memory Examples ======================");
             FixedKeywordExamples.Examples();
+            Console.WriteLine("=================    Iteration Keywords Examples ======================");
+            IterationKeywordsExamples.Examples();
         }
     }
 }