multiple conditions in if then statements

[Analysis&Solutions]

When evaluating multiple conditions in an if then statement,
all other languages I've dealt with act in an efficient manner;
if the first condition fails, save time by not evaluating
subsequent conditions.

This is helpful when working with arrays. The first condition
can act as a safeguard against exceeding the bounds of the array
in the second condition.

Unfortunately, the VB engine doesn't work that way...


Dim i As Integer = 1
Dim a() As String = New String() {"zero", "one", "two"}
Dim bound As Integer = UBound(a)

' This is okay because i is within bounds.
If i <= bound And a(i) = "one" Then
MsgBox(i & " is less than " & bound)
End If

' The second condition is evaluated even though the first
' condition is false, resulting in the following error:
' "Index was outside the bounds of the array."
i = 6
If i <= bound And a(i) = "one" Then
' DUH!
End If

 

[Tom Shelton]

Analysis&Solutions laid this down on his screen :

When evaluating multiple conditions in an if then statement,
all other languages I've dealt with act in an efficient manner;
if the first condition fails, save time by not evaluating
subsequent conditions.

This is helpful when working with arrays. The first condition
can act as a safeguard against exceeding the bounds of the array
in the second condition.

Unfortunately, the VB engine doesn't work that way...


Dim i As Integer = 1
Dim a() As String = New String() {"zero", "one", "two"}
Dim bound As Integer = UBound(a)

' This is okay because i is within bounds.
If i <= bound And a(i) = "one" Then
MsgBox(i & " is less than " & bound)
End If

' The second condition is evaluated even though the first
' condition is false, resulting in the following error:
' "Index was outside the bounds of the array."
i = 6
If i <= bound And a(i) = "one" Then
' DUH!
End If

AndAlso, OrElse

HTH

 

[Analysis&Solutions]

AndAlso, OrElse

Excellent. Thanks Tom,

--Dan

 

[Analysis&Solutions]

Thanks again to everyone here for helping me with this code. It's now
posted on GitHub, if you're interested:
http://github.com/convissor/address_standardization_solution_vb

--Dan

 

[Analysis&Solutions]

http://github.com/convissor/address_standardization_solution_vb

Oh, and any feedback on style or substance will be greatly appreciated.

Thanks,

--Dan