VB.NET Language in a Nutshell, Second Edition

Name

CObj Function

Named Arguments

No

Syntax

CObj(expression)

expression (required; any)

Return Value

expression cast as an Object data type

Description

Converts any expression that can be interpreted as an object to Object

Rules at a Glance

expression can be any data type, including a strongly typed object, as the following code fragment illustrates:

Dim oSomeClass As New CSomeClass
Dim oObj As Object
oObj = CObj(oSomeClass)

Example

The following code:

Dim obj As Object
obj = CObj("test")

casts the string "test" to type Object and places it in the Object variable obj.

Programming Tips and Gotchas

• The operation of the CObj function is possible because all VB.NET data types are either structures or objects.

• Once a data type is converted to type Object, you can display its value by calling its ToString method, as in the following code fragment:

  Dim bFlag As Boolean = True
  
  oObj = CObj(bFlag)
  MsgBox(oObj.ToString)

• Instead of using the CObj function to convert a strongly typed object to a generic Object data type, you can also use simple assignment, as the following code fragment illustrates:

  Dim oSomeClass As New CSomeClass
  Dim oObj As Object
  oObj = oSomeClass

• Like most of the conversion functions, CObj is not actually a function in the Microsoft.VisualBasic namespace. Instead, it is similar to a Visual C++ macro; the compiler translates the function call into inline code.

VB.NET/VB 6 Differences

The CObj function is new to VB.NET. The closest equivalent in VB 6 is CVar, which converts a data type ...