VB.NET Language in a Nutshell, Second Edition

Name

CBool Function

Named Arguments

No

Syntax

CBool(expression)

expression (required; String or Numeric)

Any numeric expression or a string representation of a numeric value

Return Value

expression converted to Boolean data type (True or False)

Description

Casts expression as a Boolean data type

Rules at a Glance

When a numeric value is converted to Boolean, any nonzero value is converted to True, and zero is converted to False.

If the expression to be converted is a string, the string must be capable of being evaluated as a number, or it must be "True" or "False". Any other string generates a runtime error. For example, CBool("one") results in a type mismatch error, whereas CBool("1") is converted to True, and CBool("True") is converted to True.

Programming Tips and Gotchas

• You can check the validity of the expression prior to using the CBool function by using the IsNumeric function.

• Like most of the conversion functions, CBool 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.