Name
IIf Function
Class
Microsoft.VisualBasic.Interaction
Syntax
IIf(expression, truepart, falsepart
)
-
expression
Use: Required
Data Type: Boolean
Expression to be evaluated
-
truepart
Use: Required
Data Type: Any value or expression
Expression or value to return if
expression
isTrue
-
falsepart
Use: Required
Data Type: Any value or expression
Expression or value to return if
expression
isFalse
Return Value
The value or result of the expression indicated by
truepart
or
falsepart
Description
Returns one of two results, depending on whether
expression
evaluates to
True
or False
Rules at a Glance
IIf
will evaluate only one oftruepart
orfalsepart
, depending on the value ofexpression
.The
IIf
function is the equivalent of:If
testexpression
ThenReturn truepart
ElseReturn falsepart
End If
truepart
andfalsepart
can be a variable, constant, literal, expression, or the return value of a function call.
Programming Tips and Gotchas
The
IIf
function is ideal for very simple tests resulting in single expressions. If you really feel the need,IIf
function calls can be nested; however, your code can very quickly become difficult to read. The following code fragment illustrates the use of a nestedIIf
function:Dim x As Integer x = CInt(Text1.Text) MsgBox(IIf(x < 10, "Less than ten", IIf(x < 20, _ "Less than 20", "Greater than 20")))
In previous versions of VB, developers tended to avoid the
IIf
function in favor of theIf
statement for all but the most simple uses because of its poor performance. In VB.NET, ...
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