Select...Case & If...Else!

[arpan_de]

Select...Case & If...Else - are there any advantages/disadvantages of the former over the latter or vice-versa?

[szlamany]

I believe the perceived efficiency issue is that in a SELECT/CASE with lots of CASE statements that it will jump to the END SELECT after the active CASE is met.

There is obvious syntax differences - the SELECT/CASE simply looks much better visually with a dozen options.

There is a kind of "implied hierarchy" to IF/THEN/ELSe/IF...

[arpan_de]

I believe the perceived efficiency issue is that in a SELECT/CASE with lots of CASE statements that it will jump to the END SELECT after the active CASE is met.

The same happens in If...Else statements as well; as soon as the condition is satisfied, VB runtime will jump to the End If line.......

[nerosis]

Switch or Select Statements are more standard in a situation where you have a number of possible cases. There isn't really a performance difference that you would ever notice... it's just one of those things where you have a normal way to write code.

[Static]

Select case is more efficient.. as stated... and easier to use in some cases

Like:

If X = 10 Or X = 11 Or X = 13 Then
 
ElseIf X = 12 Or (X > 14 And X < 18) Then
 
End If
 
'where as case..
 
Select Case X
    Case 10, 11, 13
    
    Case 12, 15 To 17
    
End Select

[randem]

Think about those who will follow you in coding (or maybe yourself in a few months). It would be easier to figure out what a Select Case statement does than a complex If...then...else statement.

It just plain reads BETTER!!!!

Don't Be a Will Allen!!!!!!!!

[szlamany]

The same happens in If...Else statements as well; as soon as the condition is satisfied, VB runtime will jump to the End If line.......

Not really...

Select Case lngValue
    Case 1
        ...
    Case 2
        ...
    Case 3
        ...
    Case 4
        ...
End Select

Cannot be replaced by

If lngValue = 1 Then
   ...
End If

If lngValue = 2 Then
   ...
End If

If lngValue = 3 Then
   ...
End If

If lngValue = 4 Then
   ...
End If

Without using GOTO you cannot mimic the SELECT CASE behaviour of "jumping" to the END SELECT with IF/Blocks easily.

[szlamany]

Think about those who will follow you in coding (or maybe yourself in a few months). It would be easier to figure out what a Select Case statement does than a complex If...then...else statement.

I could not agree more - maintainability of code is so much more important at times then simple old efficiency.

When we have a complex IF statement we sometimes code it like this:

booDoSomething = True
 
If booDoSomething Then
   If {check some condition to see if we really want to do this} Then
       booDoSomething = False
   End of
End If
 
If booDoSomething Then
   If {check some other condition (2) to see if we really want to do this} Then
       booDoSomething = False
   End of
End If
 
If booDoSomething Then
   If {check some other condition (3) to see if we really want to do this} Then
       booDoSomething = False
   End of
End If
 
If booDoSomething Then
   Call SomeFunction
End If

This might seem like odd code but the alternative is:

If {check some condition to see if we really want to do this} _
      or {check some other condition (2) to see if we really want to do this} _
      or {check some other condition (3) to see if we really want to do this} Then
   Call SomeFunction
End If

This alternative might appear easier to write - but visit it 6 months later and add a NOT condition or an AND/OR condition and watch the bugs fly!

[arpan_de]

The same happens in If...Else statements as well; as soon as the condition is satisfied, VB runtime will jump to the End If line.......

Not really...

szlamany, what I meant was for a condition like this:

If lngValue = 1 Then
   ...
ElseIf lngValue = 2 Then
   ...
ElseIf lngValue = 3 Then
   ...
ElseIf lngValue = 4 Then
   ...
End If

& not for the If code snippet you have cited in post #7. So

Select Case lngValue
    Case 1
        ...
    Case 2
        ...
    Case 3
        ...
    Case 4
        ...
End Select

can very well be replaced by the If...Else conditional statements I have shown above. The Select...Case equivalent of the If conditions you have cited in post #7 would be

Select Case lngValue
    Case 1
        ...
End Select
 
Select Case lngValue
    Case 2
        ...
End Select
 
Select Case lngValue
    Case 3
        ...
End Select
 
Select Case lngValue
    Case 4
        ...
End Select

Select case is more efficient.. as stated... and easier to use in some cases

Like:

Static, you have really shown a very good example to highlight the difference in readability between If....Else & Select...Case statements especially when the conditions turn out to be pretty complex.....great stufffffffff

[szlamany]

I understand what you meant now...

I personally could never use the ELSEIF statement - what I appreciate about IF/THEN/ELSE blocks are the indented nature of them.

That ELSEIF statement never made any sense to me - makes for some hard to follow logic-flow.