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Single line “if” statement in VBScript (like in C# or PHP)

posted in: Classic ASP, Programming, VBScript 0

The “single line if statement” exists in C# and VB.NET as in many other programming and script languages in the following format

lunchLocation = (dayOfTheWeek == "Tuesday") ? "Fuddruckers" : "Food Court";

The conditional ternary operator doesn’t exist out of the box, but it’s pretty easy to create your own function in VBScript:

Function IIf(bClause, sTrue, sFalse)
    If CBool(bClause) Then
        IIf = sTrue
        IIf = sFalse
    End If
End Function

You can then use this, as for the example above:

lunchLocation = IIf(dayOfTheWeek = "Tuesday", "Fuddruckers", "Food Court")

The advantage of this over using a single line If/Then/Else is that it can be directly concatenated with other strings. Using If/Then/Else on a single line must be the only statement on that line.

There is no error checking on this, and the function expects a well formed expression that can be evaluated to a boolean passed in as the clause.

It’s also worth noting that unlike a real ternary operator, both the sTrue and sFalse parameters will be evaluated regardless of the value of bClause. This is fine if you use it with strings as in the question, but be very careful if you pass in functions as the second and third parameters!

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