B4J Question Else If (expression) Then (expression) - in 1 line

a n g l o · Jul 16, 2022

the following code :

B4X:

Dim a As Int
a=2
If a =1 Then
    Log(1)
Else If a=2 Then Log(2)       
End If

does not raise any red issues / warning issues from the IDE (b4J).
but it does NOT log "2" (as expected ??).
only if the 'log(2)' moved to next line - it logs it ok.

so, if writing this way is a syntax mistake/error - the IDE should warn you about that.
and if not, it should work (as expected ??).

BTW - just tried it on vb6 ide - it's accepted and works there. (not that it binds b4x in any way).

if i'm missing something, please let me know. thank you.

jahswant · Jul 16, 2022

Yes that’s a parser failure. You have to move to the next line to the right execte.

agraham · Jul 16, 2022

No it's not a parser failure. Single line If ... Then ... has always been allowed in B4X. Check the Intellisense for If

Single line:
If condition Then true-statement [Else false-statement]
Multiline:
If condition Then
statement
Else If condition Then
statement
...
Else
statement
End If

Though if does seem to not work as expected after an Else. So while not necessarily a parser failure it does look like a bug of some sort!

PaulMeuris · Jul 16, 2022

You could also write it like this:

if on one line:

    Dim a As Int
    a=2
    If a =1 Then
        Log(1)
    Else
        If a=2 Then Log(2)
    End If

This way the single line if is on one line and nothing preceeds it.

jahswant · Jul 16, 2022

But the parser should understand that it doesn’t apply to this case !

agraham · Jul 16, 2022

jahswant said:
But the parser should understand that it doesn’t apply to this case !

Why shouldn't it apply in this case? Other than Erel decided not to support it in which case it should produce a warning. Only Erel can tell us what the original intent was.

MegatenFreak · Jul 17, 2022

There are two ways to put that example into one line:

B4X:

'Solution 1: using colon to indicate a new line:
If a =1 Then : Log(1) : Else If a=2 Then : Log(2) : End If
'Solution 2: using a ternary structure:
Log (IIf(a=1, 1, IIf(a=2, 2, "")))

Erel · Jul 17, 2022

It is considered invalid syntax. I will check why there is no parser error...

Erel · Jul 17, 2022

LucaMs · Jul 17, 2022

Maybe I'm not awake yet but in my opinion the code in the first post is fine as well, without reporting errors.

B4X:

If a =1 Then
    Log(1)
Else If a=2 Then Log(2)      
End If

jahswant · Jul 17, 2022

Erel said:
It is considered invalid syntax. I will check why there is no parser error...

I told you it’s a parser failure. There’s are other cases like this one. I don’t remember but I will post if I encounter them.

a n g l o · Jul 17, 2022

Erel said:
View attachment 131495

Erel thank you,
as for the image you uploaded :
no such red error marks here (b4j 9.8).
i belive i'm not the only one here that can say that.

i'd like to know what to do to have that error marks as well.
it may seems a little issue but belive me, it's not :

it is a project where there are more then 1700 'Else If'.
on friday i've found 1 case where the following 'Then' expresion is in the same line.
AS THERE IS NO ERROR from the IDE about that, AND the 'Then' part is ignored (treated as comment....) ==>
==> the algorithem produce a wrong calulation/result.

now, if i found 1, there maybe more.
i'd like the IDE to point me to them, otherwise, i'll have to write code to find syntax errors....

Thank you

Erel · Jul 17, 2022

a n g l o said:
no such red error marks here (b4j 9.8).

True. It will show in the next version.

MicroDrie · Jul 17, 2022

a n g l o said:
it is a project where there are more then 1700 'Else If'.

The very large number of IF / ELSE statements reminds me of the time when we had to "normalize" such a function in school, so that the duplications were removed and a simplification occurred. You often see that a specific condition often excludes several possible. This greatly reduces the number of tests.

B4J Question Else If (expression) Then (expression) - in 1 line

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