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+---
+title: "Method Implementation in Custom Controls"
+ms.date: "03/30/2017"
+dev_langs: 
+  - "csharp"
+  - "vb"
+helpviewer_keywords: 
+  - "user controls [Windows Forms], method implementation"
+  - "custom controls [Windows Forms], overloading methods"
+  - "custom controls [Windows Forms], method implementation"
+  - "methods [Windows Forms]"
+  - "methods [Windows Forms], custom controls"
+ms.assetid: 35d14fca-4bb4-4a27-8211-1f7a98ea27de
+---
+# Method Implementation in Custom Controls
+A method is implemented in a control in the same manner a method would be implemented in any other component.  
+  
+ In Visual Basic, if a method is required to return a value, it is implemented as a `Public Function`. If no value is returned, it is implemented as a `Public Sub`. Methods are declared using the following syntax:  
+  
+```vb  
+Public Function ConvertMatterToEnergy(Matter as Integer) As Integer  
+   ' Conversion code goes here.  
+End Function  
+```  
+  
+ Because functions return a value, they must specify a return type, such as integer, string, object, and so on. The arguments `Function` or `Sub` procedures take, if any, must also be specified.  
+  
+ C# makes no distinction between functions and procedures, as Visual Basic does. A method either returns a value or returns `void`. The syntax for declaring a C# public method is:  
+  
+```csharp  
+public int ConvertMatterToEnergy(int matter)  
+{  
+   // Conversion code goes here.  
+}  
+```  
+  
+ When you declare a method, declare all of its arguments as explicit data types whenever possible. Arguments that take object references should be declared as specific class types — for example, `As Widget` instead of `As Object`. In Visual Basic, the default setting `Option Strict` automatically enforces this rule.  
+  
+ Typed arguments allow many developer errors to be caught by the compiler, rather than at run time. The compiler always catches errors, whereas run-time testing is only as good as the test suite.  
+  
+## Overloaded Methods  
+ If you want to allow users of your control to supply different combinations of parameters to a method, provide multiple overloads of the method, using explicit data types. Avoid creating parameters declared `As Object` that can contain any data type, as this can lead to errors that might not be caught in testing.  
+  
+> [!NOTE]
+> The universal data type in the common language runtime is `Object` rather than `Variant`. `Variant` has been removed from the language.  
+  
+ For example, the `Spin` method of a hypothetical `Widget` control might allow either direct specification of spin direction and speed, or specification of another `Widget` object from which angular momentum is to be absorbed:  
+  
+```vb  
+Overloads Public Sub Spin( _  
+   ByVal SpinDirection As SpinDirectionsEnum, _  
+   ByVal RevolutionsPerSecond As Double)  
+   ' Implementation code here.  
+End Sub  
+Overloads Public Sub Spin(ByVal Driver As Widget) _  
+   ' Implementation code here.  
+End Sub  
+```  
+  
+```csharp  
+public void Spin(SpinDirectionsEnum spinDirection, double revolutionsPerSecond)  
+{  
+   // Implementation code here.  
+}  
+  
+public void Spin(Widget driver)  
+{  
+   // Implementation code here.  
+}  
+```  
+  
+## See also
+
+- [Events](https://docs.microsoft.com/dotnet/standard/events/index)
+- [Properties in Windows Forms Controls](properties-in-windows-forms-controls.md)