Weird bug

[Mayayana]

I just wasted hours before discovering this:

x = -18

x = x + 9: If x > 10 Then x = 10: If x < 0 Then x = 0

MsgBox x

' Returns -9, but, this works:

x = -18

x = x + 9: If x < 0 Then x = 0

MsgBox x

Why? Is only one colon allowed? I've never noticed that

problem before. It works fine in VB6.

[Evertjan.]

Post by Mayayana
x = -18
x = x + 9: If x > 10 Then x = 10: If x < 0 Then x = 0
MsgBox x

no "but", as it works according to specs!

The [original] inline form of If..Then
excludes all statements following on the same line,
as the young William Gates intended.
The multiline If..Then appeared much later in Basic.

So:

If false Then MsgBox 1 : MsgBox 2

excludes both messages.

If false Then MsgBox 1 : If true Then MsgBox 2

does likewize.

Only[!!!] the inline Else or ElseIf ends this behavour.

If false Then MsgBox 1:MsgBox 2 ElseIf true Then MsgBox 3

[Dave "Crash" Dummy]

Post by Mayayana
x = -18
x = x + 9: If x > 10 Then x = 10: If x < 0 Then x = 0
MsgBox x
x = -18
x = x + 9: If x < 0 Then x = 0
MsgBox x
Why? Is only one colon allowed? I've never noticed that
problem before. It works fine in VB6.

Operations after "Then" on the line are only carried out if the
conditional statement is true. In your first example, the condition is
false and everything else on the line is ignored. In the second example,
the condition is true and the subsequent operations are carried out.
AFAIK the only limit to the number of operations that can be chained
with colons is the character length of the line.

[Mayayana]

You both seem to be right, but for the wrong
reason. I've always known : as the same as
a line return, simply used for formatting. It
should matter what code is in between the
colons as long as they're valid lines. Yet when
I tried this exact example in VB6 it failed there,
too! I guess I need to be more careful with :
in the future.

[Evertjan.]

Post by Mayayana
You both seem to be right,

There is no "you both", if you do not quote.

Post by Mayayana
but for the wrong
reason. I've always known : as the same as
a line return, simply used for formatting. It
should matter what code is in between the
colons as long as they're valid lines.

Well, you are wrong in VBS.

VBS is not VB or VBA.

Post by Mayayana
Yet when
I tried this exact example in VB6 it failed there,

Off topic, we are talking VBS.

Post by Mayayana
in the future.

Well no, you nieed to understand how VBS works.

[Mayayana]

| Well no, you nieed to understand how VBS works.


Try this one. It seems to work fine unless there's
a multiple If/Then:

Dim x, y, z

x = 7: y = 6: z = 2: y = z + 5: x = 4

MsgBox x

[Evertjan.]

Post by Mayayana
| Well no, you nieed to understand how VBS works.
Try this one. It seems to work fine unless there's
Dim x, y, z
x = 7: y = 6: z = 2: y = z + 5: x = 4
MsgBox x

No I won't, there is no If..Then here.

If you want to explain something, please do.

[Mayayana]

| > Try this one. It seems to work fine unless there's
| > a multiple If/Then:
| >
| > Dim x, y, z
| >
| > x = 7: y = 6: z = 2: y = z + 5: x = 4
| >
| > MsgBox x
|
| No I won't, there is no If..Then here.
|

Yes. That's my point. You're talking about a
very sepcific use of colons with If/Then to execute
multiple statements. I'm talking about the other
use of colons -- to serve as line returns in order
to write compact code. The line I wrote above is
a sample. It works perfectly well. Here's another one:

Dim x, y, z

x = 4: y = "apple": z = Instr(y, "l") + 10: x = x + z

MsgBox x

Those are 4 lines written without carriage returns.
The sample I originally posted was also not a compound
If/Then. It was 3 lines of code, each a complete line
on its own, 2 of which happened to be If/Then
statements.

I'm only posting this to warn people who may
not be aware of this inconsistency. You may
not use colons as line returns. If not then this
issue will be of no concern to you. But many people
do use colons in that way, and I'm one of them.
Now I know to be on the lookout for complications
in the future.

[R.Wieser]

Mayayana,

Evertjan is right, it works as designed.

Lets look at it from another angle, and regard the following: If a condition
is met, I want both X and Y to be set to Zero. I would, and always have
written that as :

if condition then x=0: y=0

You on the other hand would be reading it as:

if condition then x=0:
y=0

To be more specific, you would not be able to write a one-line,
multy-command "then" ....

as the same as a line return, simply used for formatting

Well, that is where you problem exists. The line return terminates a
*line* (which can hold one or more commands), the colon only terminates a
single command.

It works fine in VB6.

I strongly doubt that. Using it predecessor (VB5) a line like:

if False then debug.print "1": debug.print "2"

prints neither the "1" nor the "2".

I'm talking about the other use of colons -- to serve as
line returns in order to write compact code

Suggestion: Do not try to take a feature on one programming language and
expect another one (even though deceptivly named almost the same) to adhere
to it. Each language "does its own thing". No ammount of "yes but ...."
will change anything to that I'm afraid.

Regards,
Rudy Wieser



-- Origional message

x = -18
x = x + 9: If x > 10 Then x = 10: If x < 0 Then x = 0
MsgBox x
x = -18
x = x + 9: If x < 0 Then x = 0
MsgBox x
Why? Is only one colon allowed? I've never noticed that
problem before. It works fine in VB6.

[Evertjan.]

Post by R.Wieser
Evertjan is right, it works as designed.

Thanks for enhancing my self-esteem, Rudy.

Most "weird bugs" are just misinterpreting the design.

cf 2003:
<https://groups.google.com/d/msg/microsoft.public.scripting.vbscript/P72yYHF
o16c/lGdII2Ezmb0J>

cf 2007:
<https://groups.google.com/d/msg/microsoft.public.scripting.vbscript/95IzaEP
uGpA/7DmYnVv45bMJ>

[R.Wieser]

Evertjan,

Post by Evertjan.
Thanks for enhancing my self-esteem, Rudy.

You're welcome. :-)

Post by Evertjan.
Most "weird bugs" are just misinterpreting the design.

Or, as in Mayayana's case, expecting one language to adhere to another
languages method-of-working ...

... Which I also have made myself guilty of in the past, so I cannot really
blame him. :-| :-)

Regards,
Rudy Wieser

Post by Evertjan.

Post by R.Wieser
Evertjan is right, it works as designed.

Thanks for enhancing my self-esteem, Rudy.
Most "weird bugs" are just misinterpreting the design.

<https://groups.google.com/d/msg/microsoft.public.scripting.vbscript/P72yYHF

Post by Evertjan.
o16c/lGdII2Ezmb0J>

<https://groups.google.com/d/msg/microsoft.public.scripting.vbscript/95IzaEP

Post by Evertjan.
uGpA/7DmYnVv45bMJ>
--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

[Mayayana]

| To be more specific, you would not be able to write a one-line,
| multy-command "then" ....
|
| > as the same as a line return, simply used for formatting
|
| Well, that is where you problem exists. The line return terminates a
| *line* (which can hold one or more commands), the colon only terminates a
| single command.
|
It seems that the colon terminates any line
*except* an If/Then without problem. My
example above includes 2 operations in one
segment. I don't know how you can say that's
not a line:

x = 4: y = "apple": z = Instr(y, "l") + 10: x = x + z

Those are all lines. [z = Instr(y, "l") + 10] is a
compound operation. I don't know how you're
defining a command vs a line.

A colon acts as a line break. An example is in the
WSH help, under ExecuteGlobal:

'Include multiple statements in the statement argument, using colons or
embedded line breaks to separate them.'

"Sub Proc2: Print X: End Sub"

--------------
Here's another sample that works perfectly well:

Dim FSO: Set FSO = CreateObject("Scripting.FileSystemObject"):
FSO.DeleteFile "C:\windows\desktop\test1.txt", True: Msgbox "file deleted.",
64

That's a whole script in a single line. Each segment
must be a separate line. Thus, the colon is acting
as a line return.

| > It works fine in VB6.
|
| I strongly doubt that. Using it predecessor (VB5) a line like:
|

You're right. It turns out that a double If/Then
doesn't work in VB6. That's disconcerting, as I've
been using colons for years.

For me the issue here is not what's officially
correct or who's right. The point is simply that
the design is a "gotcha". I would have expected
my complete If/Then line to be processed in
the same way as if I had used a line return. It
seems to be the only case where the colon doesn't
work properly as a line return.

The multiple statement If/Then, by contrast,
is not written in the same way. From the help:

If A > 10 Then A = A + 1 : B = B + A : C = C + B

That's not what I was writing. I wrote complete
lines that were not related:

If A > 10 then A = A + 1: If B < 10 then B = 0

Anyway, at this point anyone who uses colons
should understand what I'm talking about and be
adequately warned. That's the only reason for my
posting. I'm not concerned whether Bill Gates is
exonerated or sentenced to hang by his thumbs. :)

[Evertjan.]

Post by Mayayana
That's a whole script in a single line. Each segment
must be a separate line. Thus, the colon is acting
as a line return.

Nonsense.

A line is just a line, terminated by an end of line.
A statement is just a statement.

A statement that is not part of another statement
needs to be preceded by an end of line, a colon
or it is at the start of the code.

A statement does not need any termination.

There is no requirement for a statement
to "have" a separate line.

[Mayayana]

I knew you'd have some kind of cranky rebuttal.
I'm done. You're only further confusing a simple
point.

[Evertjan.]

"Mayayana" <***@invalid.nospam> wrote on 17 Nov 2015 in
microsoft.public.scripting.vbscript:

[you forgot to quote, in your anger perhaps]

Post by Mayayana
I knew you'd have some kind of cranky rebuttal.
I'm done. You're only further confusing a simple
point.

You think it cranky that I find a line must be a line?

What is not simple about that?

What is cranky about that?

[R.Wieser]

Mayayana,
Thats easy to explain: I never said that.

What I however *did* say that, as you have quoted in your message, "You
would not be able to write a one-line multy-command *THEN*" ....

And yes, your example is a single-line containing multiple commands
(assignments actually). But it also has got *nothing* to do with your
stated problem, the (as far as you think) quirks of the "if" command ...

Post by Mayayana
A colon acts as a line break.

Nope, it does not. The line break also has another function, namely the
termination of an(y) open "if" (in the case the "then" is, on the same line,
followed with more code).

Post by Mayayana
'Include multiple statements in the statement argument,
using colons or embedded line breaks to separate them.'

In itself that is correct. But I think you know as well as I that that is
not the full documentation about the language, and that several commands
mention their own exceptions to it.
And alas, again having nothing to do with the "if" command, and how it alter
the flow of the program. As is your "whole script in a single line." :-(

Post by Mayayana
Thus, the colon is acting as a line return.

Only if you ignore the line returns other effects, which your example code
does not make any use of.

Post by Mayayana
That's disconcerting, as I've been using colons for years.

Obviously not in VB6 .... :-D

Post by Mayayana
The point is simply that the design is a "gotcha".

Only if you tried to use this design when having used another design first.
Would you have used this design first the other design would have the
gotcha.

To quote myself:
<quote>
Suggestion: Do not try to take a feature of one programming
language and expect another one to adhere to it. Each language
"does its own thing". No ammount of "yes but ...." will
change anything to that I'm afraid.
</quote>
(typo fixed: "on one" -> "of one". Also left out a bracketed sub-sentence)

Post by Mayayana
For me the issue here is not what's officially correct or who's right

Than please don't try to create a problem where there is none. Its just a
difference in what you think is true (how something should work), and what a
programming/scripting language has been defined to how it works.


But a question: Have you already thought about the problem I described in my
initial reply, where I wanted to set both "X" and "Y" to zero when a
condition was met ?

How would you, using your approach, set that "Y" to zero ? -- without
turning the "if" in a multi-line construction ofcourse.

Maybe the designer of the programming language saw something you (still)
have not .... :-)

Regards,
Rudy Wieser


-- Origional message

Post by Mayayana
| To be more specific, you would not be able to write a one-line,
| multy-command "then" ....
|
| > as the same as a line return, simply used for formatting
|
| Well, that is where you problem exists. The line return terminates a
| *line* (which can hold one or more commands), the colon only terminates a
| single command.
|
It seems that the colon terminates any line
*except* an If/Then without problem. My
example above includes 2 operations in one
segment. I don't know how you can say that's
x = 4: y = "apple": z = Instr(y, "l") + 10: x = x + z
Those are all lines. [z = Instr(y, "l") + 10] is a
compound operation. I don't know how you're
defining a command vs a line.
A colon acts as a line break. An example is in the
'Include multiple statements in the statement argument, using colons or
embedded line breaks to separate them.'
"Sub Proc2: Print X: End Sub"
--------------
FSO.DeleteFile "C:\windows\desktop\test1.txt", True: Msgbox "file deleted.",
64
That's a whole script in a single line. Each segment
must be a separate line. Thus, the colon is acting
as a line return.
| > It works fine in VB6.
|
|
You're right. It turns out that a double If/Then
doesn't work in VB6. That's disconcerting, as I've
been using colons for years.
For me the issue here is not what's officially
correct or who's right. The point is simply that
the design is a "gotcha". I would have expected
my complete If/Then line to be processed in
the same way as if I had used a line return. It
seems to be the only case where the colon doesn't
work properly as a line return.
The multiple statement If/Then, by contrast,
If A > 10 Then A = A + 1 : B = B + A : C = C + B
That's not what I was writing. I wrote complete
If A > 10 then A = A + 1: If B < 10 then B = 0
Anyway, at this point anyone who uses colons
should understand what I'm talking about and be
adequately warned. That's the only reason for my
posting. I'm not concerned whether Bill Gates is
exonerated or sentenced to hang by his thumbs. :)

[Evertjan.]

Post by R.Wieser
Maybe the designer of the programming language saw something you (still)
have not .... :-)

The only bug here that was introduced in VBS is
that the following is illogically allowed:

If boolean Then statement Else statement End If

as the "End If" is only part of the multiline If,
not used or needed in the inline If syntax.

Correct is:

If boolean Then statement Else statement

It is said that years ago [2003??] MS did put in an exception
for that error during an update and immediately sites
like cnn.com came tumbling down, so they restored the error.

[R.Wieser]

Evertjan.

Post by Evertjan.
The only bug here that was introduced in VBS is

Please explain why its illogical. All I see is a method to terminate a
"then" before an line-end is encountered. It would definitily solve
Mayayana's initial problem:

x = x + 9: If x > 10 Then x = 10 *end if*: If x < 0 Then x = 0

That a line-end *can* be used to terminate a single-line "if" does not mean
it should be the *only* way to do it. :-)

Post by Evertjan.
If boolean Then statement Else statement

Nope. Its just how quite a few (but definitly not all!) languages have
defined it. It does not mean its the *only way* anyone may implement it in
his language.

I know of languages which use your above description and work as Mayayana
described (continuing after a "then" if no "else" is found, or after the
first command after the "else").

Ofcourse, several of those languages have "command grouping" commands and/or
symbols, making it again possible to have a "then" or "else" execute an
abitrary number of commands/equations. Just think of how C++ does it, using
"{" and "}" to group commands together.

VBS (and a number of other languages) do not have such command-grouping
symbols/commands/methods, so they needed to think of something else.

Regards,
Rudy Wieser

Post by Evertjan.

Post by R.Wieser
Maybe the designer of the programming language saw something you (still)
have not .... :-)

The only bug here that was introduced in VBS is
If boolean Then statement Else statement End If
as the "End If" is only part of the multiline If,
not used or needed in the inline If syntax.
If boolean Then statement Else statement
It is said that years ago [2003??] MS did put in an exception
for that error during an update and immediately sites
like cnn.com came tumbling down, so they restored the error.
--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

[Evertjan.]

Post by R.Wieser

Post by Evertjan.
If boolean Then statement Else statement

Nope. Its just how quite a few (but definitly not all!) languages have
defined it. It does not mean its the *only way* anyone may implement
it in his language.
I know of languages which use your above description and work as
Mayayana described (continuing after a "then" if no "else" is found, or
after the first command after the "else").

I am not interested in "other languages" here,
only in the developement of this:

Beginners All-purpose Symbolic Instruction Code.

Seen in the light of other languages,
Basic was as bad as Edsger Wybe Dijkstra promised it to be, IMO:

"BASIC programmers are mentally mutilated beyond hope of regeneration"
said Edsger Wybe Dijkstra in
How do we tell truths that might hurt? (1975-06-18)

[In fact our Edsger was primarily fighting a language that did everything
with GoTo, no subroutines, no functions, so no modularity or black box
testing, just making a unresolvable knot of even the smallest logical
construct. And no possibility to sensibly name variables other than by a
single Capital letter plus a number. Referring to his 1975 words however is
a joy in itself]

=========================

In principio [in the beginning] there was only:

If boolean GoTo linenumber

then came:

If boolean Then statement

and then:

If boolean Then statement Else statement

after that the multiline If was introduced:

If boolean Then
statement
Else
statement
End If

The multiline "ElseIf" addition even later.

The "End If" was never, formally or otherwise planned, introduced
in the older single line If, it only was discovered in this NG
and recognised as a bug by MS.

Post by R.Wieser
Ofcourse, several of those languages have "command grouping"

[snip]

[Evertjan.]

Post by Evertjan.
"BASIC programmers are mentally mutilated beyond hope of regeneration"
said Edsger Wybe Dijkstra in
How do we tell truths that might hurt? (1975-06-18)

<https://www.cs.utexas.edu/users/EWD/ewd04xx/EWD498.PDF>

[R.Wieser]

Evertjan,

Post by Evertjan.
I am not interested in "other languages" here,
Beginners All-purpose Symbolic Instruction Code.

Than our conversation ends here.

Not because of the language, but as you are going into the realm of the
"what if's". I have no interest in second-guessing what a language designer
might decide *his* language should evolve in.

Post by Evertjan.
Seen in the light of other languages,
Basic was as bad as Edsger Wybe Dijkstra

Which version of it please ?

Post by Evertjan.
"BASIC programmers are mentally mutilated beyond hope of regeneration"
said Edsger Wybe Dijkstra in
How do we tell truths that might hurt? (1975-06-18)

So, you take that statement outof its context and time and are trying to put
it on several BASIC variants that have evolved sinds than, meaning for the
last 40 years ?

BASIC *might* have been bad in those days, but so is *any* programming
language in the hands of a nitwit. I've seen enough junk over the years, in
all sorts of languages (PHP, Java, .NET, C{something}, BASIC, you name it).

Post by Evertjan.
The "End If" was never, formally or otherwise planned, introduced
in the older single line If, it only was discovered in this NG
and recognised as a bug by MS.

So ? They *stated* it was a bug, but I doubt it. And even if it was
introduced by accident, what does that matter if the result is quite
usefull, and does not break anything else (read: is consistent with the rest
of the language) ?

You know what *I* find odd ? That an "end if" may be followed by a colon
and than more code. That certainly breaks the "multi-line if" approach. :-)

Ofcorse, *not* allowing that would be an exception to the rule that *any*
command may be followed by a colon ...

Post by Evertjan.

Post by R.Wieser
Ofcourse, several of those languages have "command grouping"

Too bad you have taken a stance, bluntly disregarding this, quite important
difference between two types of implementation of a language, where VBScript
is in the group of "do not have it", and has, to solve it, created the "end
if".

The *only* squabble we have here is if it should be allowed in a single-line
"if" or not. Nothing more, nothing less.

Regards,
Rudy Wieser

Post by Evertjan.

Post by R.Wieser

Post by Evertjan.
If boolean Then statement Else statement

Nope. Its just how quite a few (but definitly not all!) languages have
defined it. It does not mean its the *only way* anyone may implement
it in his language.
I know of languages which use your above description and work as
Mayayana described (continuing after a "then" if no "else" is found, or
after the first command after the "else").

I am not interested in "other languages" here,
Beginners All-purpose Symbolic Instruction Code.
Seen in the light of other languages,
"BASIC programmers are mentally mutilated beyond hope of regeneration"
said Edsger Wybe Dijkstra in
How do we tell truths that might hurt? (1975-06-18)
[In fact our Edsger was primarily fighting a language that did everything
with GoTo, no subroutines, no functions, so no modularity or black box
testing, just making a unresolvable knot of even the smallest logical
construct. And no possibility to sensibly name variables other than by a
single Capital letter plus a number. Referring to his 1975 words however is
a joy in itself]
=========================
If boolean GoTo linenumber
If boolean Then statement
If boolean Then statement Else statement
If boolean Then
statement
Else
statement
End If
The multiline "ElseIf" addition even later.
The "End If" was never, formally or otherwise planned, introduced
in the older single line If, it only was discovered in this NG
and recognised as a bug by MS.

Post by R.Wieser
Ofcourse, several of those languages have "command grouping"

[snip]
--
Evertjan.
The Netherlands.
(Please change the x'es to dots in my emailaddress)

[Mayayana]

| > A colon acts as a line break.
|
| Nope, it does not.

Try my sample without the colons:

Dim FSO Set FSO = CreateObject("Scripting.FileSystemObject") FSO.DeleteFile
"C:\windows\desktop\test.txt", True Set FSO = Nothing

It won't work. You'll get an error "Expected end of statement"
before Set. That doesn't happen with the colons. I don't
see why this should be so hard to explain. If/Then can have
multiple actions assigned using colons. Colons are *also*
valid carriage return characters. They're two entirely different
functions. The problem comes when one of those lines
contains If/Then, even if the syntax does not indicate
multiple statements for execution. In that case it *should*
be treated the same as if the code was on separate lines,
but it isn't.

[R.Wieser]

Mayayana,
[snip]

Post by Mayayana
It won't work.

You have not used *either* of the available methods to end a
command/equation and are complaining that it won't work ? Really ? :-D

And no, that you can either use a colon or a line-break between the "True"
and "Set" still does not mean they are the same (as I already tried to
explain).

Regards,
Rudy Wieser.

Post by Mayayana
| > A colon acts as a line break.
|
| Nope, it does not.
Dim FSO Set FSO = CreateObject("Scripting.FileSystemObject")

FSO.DeleteFile

Post by Mayayana
"C:\windows\desktop\test.txt", True Set FSO = Nothing
It won't work. You'll get an error "Expected end of statement"
before Set. That doesn't happen with the colons. I don't
see why this should be so hard to explain. If/Then can have
multiple actions assigned using colons. Colons are *also*
valid carriage return characters. They're two entirely different
functions. The problem comes when one of those lines
contains If/Then, even if the syntax does not indicate
multiple statements for execution. In that case it *should*
be treated the same as if the code was on separate lines,
but it isn't.

[R. Roesler]

Post by Mayayana
x = -18
x = x + 9: If x > 10 Then x = 10: If x < 0 Then x = 0
MsgBox x
x = -18
x = x + 9: If x < 0 Then x = 0
MsgBox x
Why? Is only one colon allowed? I've never noticed that
problem before. It works fine in VB6.

That's really easy. The first expression does not work, because there is
no /End If/ or /ElseIf/. And I am very sceptical that this code works in
VB6. Try this one:
x = x + 9: If x > 10 Then x = 10: ElseIf x < 0 Then x = 0
^^^^
A blocked *If* statement must be the _first_ statement on a _line_. The
block *If* _must_ _end_ with an *End* *If* statement. How else the
interpreter should recognize on which position the *If* statement is
over? Scripting only works for Dummys 8-O and for frustrated ones.

And that is your given statement in blocked code:

x = -18
x = x + 9
If x > 10 Then
x = 10
If x < 0 Then
x = 0
End If
End If

That makes no sense. Do you see the benefit of structered code? It makes
the code easier to read and to understand and detecting of errors is
more simple.