VB.NET Language in a Nutshell, Second Edition

Name

AddressOf Operator

Syntax

AddressOf procedurename

procedurename (required)

The name of a procedure that is referenced by the procedure delegate

Description

The AddressOf operator returns a procedure delegate instance that references a specific procedure.

The AddressOf operator is used in the following situations:

• If a parameter to a procedure (a VB procedure or a Win32 API function) requires a function pointer (the address of a function), then we can pass the expression:

  AddressOf functionname

  where functionname is the name of the function. This function is called a callback function.

• AddressOf is also used to create delegate objects, as in:

  delg = New ADelegate(AddressOf obj.AMethod)

• AddressOf is used to bind event handlers to events through the AddHandler statement:

  AddHandler Form1.Click, AddressOf Me.Form1Click

Examples of all three applications of AddressOf can be found in Section 7.1 in Chapter 7.

VB.NET/VB 6 Differences

In VB 6, the AddressOf operator can only be used in a call to a Windows API function. Moreover, the argument passed to AddressOf must be the name of a procedure in a standard code module. However, in VB.NET these restrictions no longer apply.