Menu
I recently asked a question about IIf vs. If and found out that there is another function in VB called If which basically does the same thing as IIf but is a short-circuit.
Does this If function perform better than the IIf function? Does the If statement trump the If and IIf functions?
887
Both the IF and IIF first check if the test is true; but the IIF then tests if the value is False. IF doesn't test for the False component – it treats everything not True in the same way. IIF handles those items that aren't True or False (or Unknown) differently to IF.
The key difference between IF and IIF is that the former is a statement IF test THEN value END IF test THEN value ELSE else END. And the latter is a function IIF(test, then, else, [unknown])
You can use IIf anywhere you can use expressions. You use IIf to determine if another expression is true or false. If the expression is true, IIf returns one value; if it is false, IIf returns another. You specify the values IIf returns.
Tableau IIF Function This function returns BOOLEAN results and categorizes them into 3 categories: TRUE, FALSE, and UNKNOWN. Similar to the IF Statement Tableau, IIF Statement returns a TRUE value when the conditional expression is satisfied, and a FALSE value for a failed condition.
Damn, I really thought you were talking about the operator all along. ;-) Anyway …
Does this If function perform better than the IIf function?
Definitely. Remember, it's built into the language. Only one of the two conditional arguments has to be evaluated, potentially saving a costly operation.
Does the If statement trump the If and IIf functions?
I think you can't compare the two because they do different things. If your code semantically performs an assignment you should emphasize this, instead of the decision-making. Use the If operator here instead of the statement. This is especially true if you can use it in the initialization of a variable because otherwise the variable will be default initialized, resulting in slower code:
Dim result = If(a > 0, Math.Sqrt(a), -1.0)
' versus
Dim result As Double ' Redundant default initialization!
If a > 0 Then
result = Math.Sqrt(a)
Else
result = -1
End If
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
