add overriding

TicketSystem/Order.cs

@@ -38,7 +38,7 @@ namespace TicketSystem
                     price += t.price;
                     break;
                 case TicketType.Adult:
-                    t = new Adult();
+                    t = new Ticket();
                     tickets.Add(t);
                     price += t.price;
                     break;

TicketSystem/TicketSystem.csproj

@@ -42,7 +42,6 @@
         <Compile Include="Order.cs" />
         <Compile Include="Program.cs" />
         <Compile Include="Properties\AssemblyInfo.cs" />
-        <Compile Include="Tickets\Adult.cs" />
         <Compile Include="Tickets\Child.cs" />
         <Compile Include="Tickets\Student.cs" />
         <Compile Include="Tickets\Ticket.cs" />

TicketSystem/Tickets/Adult.cs

@@ -1,17 +0,0 @@
-namespace TicketSystem.Tickets
-{
-    public class Adult: Ticket
-    {
-        public int price { get; }
-
-        public Adult()
-        {
-            price = 20;
-        }
-
-        public int PriceWithReduction()
-        {
-            return price - price/100*20;
-        }
-    }
-}

TicketSystem/Tickets/Ticket.cs

@@ -7,9 +7,17 @@
         Adult
     }
 
-    public interface Ticket
+    public class Ticket
     {
-        int price { get; }
-        int PriceWithReduction();
+        public int price { get; }
+        public Ticket()
+        {
+            price = 20;
+        }
+
+        public int PriceWithReduction()
+        {
+            return price - price/100*20;
+        }
     }
 }