Assign value if not exist in Visual Basic .NET

In Visual Basic .NET, you can use the conditional operator If to assign a value to a variable if it does not already exist.

Here is an example code:

Dim x As Integer
If x = Nothing Then
    x = 10
End If

In this example, we declare a variable x of type Integer. If x does not have a value assigned to it yet, which is determined by the x = Nothing check, then we assign a value of 10 to it.

Alternatively, you can use a shorthand notation, the null-coalescing operator ??, to achieve the same result with less code:

Dim y As Integer = 0
Dim z As Integer = If(y, 10)

In this example, we declare a variable y and set its value to 0. We then assign z to the result of If(y, 10), which will be 10 since y is not Nothing. If y was Nothing, then z would be assigned the value of 0 since 0 is considered false.