Initial data commit

Task/Singleton/C-sharp/singleton-1.cs

@@ -0,0 +1,16 @@
+public sealed class Singleton1 //Lazy: Yes ||| Thread-safe: Yes ||| Uses locking: Yes
+{
+    private static Singleton1 instance;
+    private static readonly object lockObj = new object();
+
+    public static Singleton1 Instance {
+        get {
+            lock(lockObj) {
+                if (instance == null) {
+                    instance = new Singleton1();
+                }
+            }
+            return instance;
+        }
+    }
+}