Case as to If?

[ObsidianWolf]

I have seen tons of code in my few years of coding and more then not people use If instead of Case, when Case would make things a bit more organized.  What do you think?

[Spht]

You generally should use the If statement if there's a two-way comparison (yes or no; if or else). Use Select Case when you want to run multiple checks. I never use "ElseIf." Example:

Code Select Expand

Select Case Number
   Case 1
   Case 2
   Case 3
End Select

Don't do,

Code Select Expand

If Number = 1 Then
ElseIf Number = 2 Then
ElseIf Number = 3 Then
End If

This requires more CPU cycles as opposed to a Select Case.

[iago]

Yeah, like what spht said, Case is much quicker, since it's a single jmp using a table, but it can't be used to compare numbers (<, >, etc.).  

[Skywing]

Yeah, like what spht said, Case is much quicker, since it's a single jmp using a table, but it can't be used to compare numbers (<, >, etc.).  

This is probably not (always?) true for VB, because you can use Case on stuff like strings and soforth which would invalidate the optimizations possible with a C switch.

[iago]

That's true.  I have no idea how it's implemented in VB, but at least in C++ it's a lot faster.

[Adron]

I never use "ElseIf."

I use ElseIf every once in a while. I suppose Select Case could be used, but it don't like using that with nonconstant cases. Example:

Code Select Expand


If a Then
ElseIf b Then
ElseIf c Then
ElseIf d Then
Else
End If


vs

Code Select Expand


Select Case True
Case a
Case b
Case c
Case d
Case Else
End Select


[Puzzle]

I use Select Case wherever I can, but Select Case is somewhat limited compared to If/Then.

[Spht]

I use Select Case wherever I can, but Select Case is somewhat limited compared to If/Then.

It is? How so?

[Puzzle]

Maybe I should rephrase. Its not exactly more limited, but gets really confusing if you would use it to replace a large nested If/Then.

[Grok]

Select Case is most excellent for implementing 'AND' and 'NAND' structures.  My favorite usage!

Code Select Expand

'  make sure all conditions have been met...
Result = False
Select Case False
Case A = 15
Case B$ = "Check"
Case C > 11.30
Case Else
   'all conditions true!
   Result = True
End Select
MsgBox "All Conditions have " & IIF(Result, " ", "NOT ") & "been met!"


[Adron]

Yes, it does work for those, but I find those much easier to understand when structured more english-language-like; "if this and that then bla".

[TheMinistered]

... but it can't be used to compare numbers (<, >, etc.).

iago, this is not true.  Grok even prooved it in his above example where if a specific case was greater than 11.30 then the code under it would be executed.  However, I believe grok did make a simple syntax error.  In order to do operations like that, you require the help of the 'Is' operator.

Code Select Expand


Select Case 100
   Case Is > 10
       'omg this case is greater than 10!
   Case Is < 0
       'omg this case is not less than 0!
End Select




[CupHead]

iago, this is not true.  Grok even prooved it in his above example where if a specific case was greater than 11.30 then the code under it would be executed.  However, I believe grok did make a simple syntax error.  In order to do operations like that, you require the help of the 'Is' operator.

Code Select Expand


Select Case 100
   Case Is > 10
       'omg this case is greater than 10!
   Case Is < 0
       'omg this case is not less than 0!
End Select




I don't think there's any syntax error.  If you'll look at Grok's code, you'll see his Select statement is "Select Case False".  This means that in order to do a comparison, he needs to use the variable like C > 100 or whatever.  If he uses Is, then the statement becomes False > 100 and not the variable C that he wanted compared.

[TheMinistered]

Gogo cuphead!

[Fleet-]

I was told by "professionals", that if statements were naturally quicker, is this true?