Type Conversion Functions | Visual BasicR. NET Unleashed


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	Visual Basic .NET Unleashed By Paul Kimmel
	Table of Contents

	Chapter 2. Out with the Old, In with the New

Type Conversion Functions

Earlier in the chapter, I recommended that you use Option Strict On and Option Explicit On. These settings will let the compiler help you catch errors at compile-time because they preclude a lot of implicit type conversions. You still need a good way to convert data from one type to another. To this end Visual Basic .NET includes dozens of type conversion capabilities.

Also noted throughout this chapter is the introduction of the ToString method in the Object class. Because every class and structure is an Object, every type contains a ToString conversion method. Many types also contain a method that takes a string argument and converts it to a specific type. For example, in the DateTime type, the Shared Parse method converts a string to a DateTime. The two statements below demonstrate converting a string to a DateTime and a DateTime back to a string, respectively.

 Dim ADate As DateTime = DateTime.Parse("12:00:00 AM") Dim AString As String = ADate.ToString()

Many of the VB6 conversions have been carried over to VB .NET; a few have been replaced to support new types. In VB6, the conversion functions took an expression of a specific type or variant. In VB .NET the argument type is an Object, which means that you can pass any subclass of an Object that makes sense for the specific kind of conversion. Table 2.9 lists the VB6 conversion functions and their VB .NET replacements .

Table 2.9. VB6 Conversion Functions and Their VB .NET Replacements

VB6	VB .NET	Description	Range
CBool	CBool	Converts Object to Boolean Type	Valid string or numeric expression
CByte	CByte	Converts Object To Byte	0 to 255
None	CChar	Converts Object to Char	0 to 65535
CCur	CDec	Converts Object to Decimal	See VB6's CDec below
CDate	CDate	Converts Object to DateTime	Any valid date or time value
CDbl	CDbl	Converts Object to Double	Any valid Double value (see Table 2.3)
CDec	CDec	Converts Object to Decimal	Any valid Decimal value (see Table 2.3)
CInt	CInt	Converts Object To Integer	Any valid Integer value (see Table 2.3)
CLng	CLng	Converts Object to Long	Any valid Long value (see Table 2.3)
CSng	CSng	Converts Object to Single	Any valid Single value
CStr	CStr	Converts Object to String	Any valid String
CVar	CObj	Converts Object to Object	Any value
None	CShort	Converts Object to Short	Any valid Short (see Table 2.3)

As you can determine from Table 2.9, most conversion functions were carried over to VB .NET. Where the VB6 column contains None, no VB6 conversion function exists.

For reference, see Appendix A, "VB 6 Programming Element Changes in VB .NET."


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