VB.NET Language in a Nutshell, Second Edition

Name

CByte Function

Named Arguments

No

Syntax

CByte(expression)

expression (required; String or Numeric)

A string or numeric expression that evaluates to a number between 0 and 255

Return Value

expression converted to Byte data type

Description

Converts expression to a Byte data type

Rules at a Glance

• If the expression to be converted is a string, the string must be capable of conversion to a numeric expression; this can be checked using the IsNumeric function.

• If expression evaluates to less than 0 or more than 255, a runtime error is generated.

• If the value of expression is not a whole number, CByte rounds the number prior to conversion.

Example

If IsNumeric(sMyNumber) Then
    If val(sMyNumber) >= 0 and val(sMyNumber) <= 255 Then
        BytMyNumber = CByte(sMyNumber)
    End If
End If

Programming Tips and Gotchas

• Check that the value you pass to CByte is neither negative nor greater than 255.

• Use IsNumeric to ensure that the value passed to CByte can be converted to a numeric expression.

• When using CByte to convert floating point numbers, fractional values up to but not including .5 are rounded down, while values above but not including .5 are rounded up. Values whose fractional component is exactly equal to .5 are rounded up if their integral component is odd and down if their integral component is even.

• The CByte function converts an expression to an unsigned byte data type. To convert expression to a signed byte data type, create an instance of the SByte class and call its Parse method.

• Like most ...