Bizzare behavior of IF..THEN
 

Having in times past encountered very freakish behavior of IF...THE
clauses, I now wish to bring up some of my observations for commen
and possible explanation. Below are 4 trumped-up cases each showin
the evaluation, or lack of it, of the conditions set out in eac
routine. Cases A and B are straightforward as they conform to what w
might expect. Namely, there is indication of serial evaluation of al
the conditions- whether met or not.

By contrast, Cases C and D betray the norm, at least seemingly so, a
conditions which should be positively evaluated appear to be untouched
(see the commented annotations for full appreciation).

Case A Case B
'all 4 conds evaluated 'all 4 conds evaluated
Sub test2() Sub test3()
If 4 < 5 Then If 4 < 5 Then 'evaluated
MSGBOX [/b]\"4<5\" *MSGBOX *\"4<5\"
IF 4 3 THEN END IF
*MSGBOX *\"43\" IF 8 10 THEN 'EVALUATED
IF 4 = 4 THEN MSGBOX \"810\"
*MSGBOX *\"4=4\" END IF
ELSE IF 3 = 3 THEN 'EVALUATED
MSGBOX \"OTHER\" *MSGBOX* \"3=3\"
END IF ELSE 'EVALUATED
END IF MSGBOX \"OTHER\"
END IF END IF
END SUB END SUB


CASE C CASE D
* 'NONE IS EVALUATED INCLUDING COND
Sub test1() Sub test4()
If 4 < 5 Then 'evaluated If 12 < 5 Then
MSGBOX* \"4<5\" MSGBOX \"12<5\"
IF 8 10 THEN*'NOT EVALUATED* IF 8 10 THEN
MSGBOX \"810\" MSGBOX \"810\"
IF 3 = 3 THEN *'NOT EVALUATED* IF 3 = 3 THEN *'NOT EVALUATE
MsgBox "3=3" MsgBox "3=3"
Else [b]'not evaluated* Else
MsgBox "other" MsgBox "other"
End If End If
End If End If
End If End If
End Sub End Sub

Bolded MsgBox refers to positive evaluation as it springs to life.

Your comments are welcomed.

Myle

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Bizzare behavior of IF..THEN
 

Hello Myles,

What has part of the logic flow has you confused? What results were yo
trying to achieve that you didn't?

Sincerely,
Leith Ros

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Bizzare behavior of IF..THEN
 

Hi Ross,

Forget about Cases A and B. In both Cases C and D, we would expect th
line: *If 3 = 3 Then * to be positively evaluated and consequently ge
the *MsgBox "3=3"* to show. This doesn't happen, for some reason, i
there is one.


Myle

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Bizzare behavior of IF..THEN
 

Hello Myles,

Let's deconstruct example "C"

Sub test3()
If 4 < 5 Then 'evaluated
MsgBox "4<5"
If 8 10 Then 'not evaluated
MsgBox "810"
If 3 = 3 Then 'not evaluated
MsgBox "3=3"
Else 'not evaluated
MsgBox "other"
End If
End If
End If
End Sub

First off, this is a group of 3 nested IF statements. The condition o
the first statement determines whether execution passes to the nex
statement.

Since 4 is less than 5 in the first statement, the message box display
the fact. Executions now passes to the second nested IF statement.

Since the condition 8 10 is false, execution passes to the End Su
statement because it is the next executable line of code.

The third IF "3=3" never executes because of the second IF being false


Sincerely,
Leith Ros

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Bizzare behavior of IF..THEN
 

How about reposting in a readable format?

Tim


"Myles" wrote in
message ...

Having in times past encountered very freakish behavior of IF...THEN
clauses, I now wish to bring up some of my observations for comment
and possible explanation. Below are 4 trumped-up cases each showing
the evaluation, or lack of it, of the conditions set out in each
routine. Cases A and B are straightforward as they conform to what we
might expect. Namely, there is indication of serial evaluation of all
the conditions- whether met or not.

By contrast, Cases C and D betray the norm, at least seemingly so, as
conditions which should be positively evaluated appear to be untouched.
(see the commented annotations for full appreciation).

Case A Case B
'all 4 conds evaluated 'all 4 conds evaluated
Sub test2() Sub test3()
If 4 < 5 Then If 4 < 5 Then 'evaluated
MSGBOX [/b]\"4<5\" *MSGBOX *\"4<5\"
IF 4 3 THEN END IF
*MSGBOX *\"43\" IF 8 10 THEN 'EVALUATED
IF 4 = 4 THEN MSGBOX \"810\"
*MSGBOX *\"4=4\" END IF
ELSE IF 3 = 3 THEN 'EVALUATED
MSGBOX \"OTHER\" *MSGBOX* \"3=3\"
END IF ELSE 'EVALUATED
END IF MSGBOX \"OTHER\"
END IF END IF
END SUB END SUB


CASE C CASE D
* 'NONE IS EVALUATED INCLUDING COND3
Sub test1() Sub test4()
If 4 < 5 Then 'evaluated If 12 < 5 Then
MSGBOX* \"4<5\" MSGBOX \"12<5\"
IF 8 10 THEN*'NOT EVALUATED* IF 8 10 THEN
MSGBOX \"810\" MSGBOX \"810\"
IF 3 = 3 THEN *'NOT EVALUATED* IF 3 = 3 THEN *'NOT EVALUATED
MsgBox "3=3" MsgBox "3=3"
Else [b]'not evaluated* Else
MsgBox "other" MsgBox "other"
End If End If
End If End If
End If End If
End Sub End Sub

Bolded MsgBox refers to positive evaluation as it springs to life.

Your comments are welcomed.

Myles


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Bizzare behavior of IF..THEN
 

Hi

It's very confusing, maybe you try to explayn more clearly.

In general, possible syntax variations for IF clause a

1. (only LogicalCondition1 is taken into account)
If LogicalCondition Then Response

2. (the response for 1st True condition is returned. When no condition is
filled, the response for Else is returned)
If LogicalCondition1 Then
Response1
ElseIf LogicalCondition2 Then
Response2
....
Else LogicalConditionN Then
ResponseN
End If

3. (either Resonse1 or Response2 are returned)
Iif(LogicalCondition,Response1,Response2)

A common point for all variants is, that always only one response (or no
responses) is returned. I somehow get the impression, that you are trying to
get several responses, are you?


--
Arvi Laanemets
( My real mail address: arvi.laanemets<attarkon.ee )


"Myles" wrote in
message ...

Having in times past encountered very freakish behavior of IF...THEN
clauses, I now wish to bring up some of my observations for comment
and possible explanation. Below are 4 trumped-up cases each showing
the evaluation, or lack of it, of the conditions set out in each
routine. Cases A and B are straightforward as they conform to what we
might expect. Namely, there is indication of serial evaluation of all
the conditions- whether met or not.

By contrast, Cases C and D betray the norm, at least seemingly so, as
conditions which should be positively evaluated appear to be untouched.
(see the commented annotations for full appreciation).

Case A Case B
'all 4 conds evaluated 'all 4 conds evaluated
Sub test2() Sub test3()
If 4 < 5 Then If 4 < 5 Then 'evaluated
MSGBOX [/b]\"4<5\" *MSGBOX *\"4<5\"
IF 4 3 THEN END IF
*MSGBOX *\"43\" IF 8 10 THEN 'EVALUATED
IF 4 = 4 THEN MSGBOX \"810\"
*MSGBOX *\"4=4\" END IF
ELSE IF 3 = 3 THEN 'EVALUATED
MSGBOX \"OTHER\" *MSGBOX* \"3=3\"
END IF ELSE 'EVALUATED
END IF MSGBOX \"OTHER\"
END IF END IF
END SUB END SUB


CASE C CASE D
* 'NONE IS EVALUATED INCLUDING COND3
Sub test1() Sub test4()
If 4 < 5 Then 'evaluated If 12 < 5 Then
MSGBOX* \"4<5\" MSGBOX \"12<5\"
IF 8 10 THEN*'NOT EVALUATED* IF 8 10 THEN
MSGBOX \"810\" MSGBOX \"810\"
IF 3 = 3 THEN *'NOT EVALUATED* IF 3 = 3 THEN *'NOT EVALUATED
MsgBox "3=3" MsgBox "3=3"
Else [b]'not evaluated* Else
MsgBox "other" MsgBox "other"
End If End If
End If End If
End If End If
End Sub End Sub

Bolded MsgBox refers to positive evaluation as it springs to life.

Your comments are welcomed.

Myles


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Bizzare behavior of IF..THEN
 

Hi Ross,

In the face of the execution behavior, your explanation sound
plausible. I am however still struggling to come to terms with th
logic behind it.

Is it not intuitively appealing that excecution should terminate onl
when a condition evaluates to TRUE? Put another way, conventiona
reasoning would demand that the code should keep on "searching" pas
FALSE evaluations until a TRUE evaluation is met, and then only exi
the sub. It is all a bit of convoluted logic to me

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Bizzare behavior of IF..THEN
 

On Tue, 31 Jan 2006 08:04:21 -0600, Myles
wrote:


Hi Ross,

In the face of the execution behavior, your explanation sounds
plausible. I am however still struggling to come to terms with the
logic behind it.

Is it not intuitively appealing that excecution should terminate only
when a condition evaluates to TRUE? Put another way, conventional
reasoning would demand that the code should keep on "searching" past
FALSE evaluations until a TRUE evaluation is met, and then only exit
the sub. It is all a bit of convoluted logic to me.

It seems logical to me; you construct a statement so that if the test is true,
do this; and if the test is false; do that.

If you want it to do further testing if a test is false, then you need to make
doing those tests a consequence of the false result.


--ron

Bizzare behavior of IF..THEN
 

Hi Ron,

you wrote inter alia:
If you want it to do further testing if a test is false, then you nee
to make doing those tests a consequence of the false result.


Since the code exits upon encountering a FALSE evaluation, could yo
please give an illustration of how you can base your tests on -
consequence of the false result-


Thanks

Myle

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Bizzare behavior of IF..THEN
 

On Tue, 31 Jan 2006 09:24:36 -0600, Myles
wrote:


Hi Ron,

you wrote inter alia:
If you want it to do further testing if a test is false, then you need
to make doing those tests a consequence of the false result.


Since the code exits upon encountering a FALSE evaluation, could you
please give an illustration of how you can base your tests on -a
consequence of the false result-


Thanks

Myles

You need to use the proper syntax. Using either Else or ElseIF for the nested
testing. (See HELP for the IF...Then...Else Statement)

============================
Sub fooD()
If 12 < 5 Then
MsgBox ("12<5")
Else
If 8 10 Then
MsgBox ("810")
Else
If 3 = 3 Then
MsgBox ("3=3")
Else
MsgBox ("other")
End If
End If
End If

End Sub
=============================

This now displays in the message box "3=3"

Or, using the Elseif:

==================================
Sub fooD()

If 12 < 5 Then
MsgBox ("12<5")
ElseIf 8 10 Then
MsgBox ("810")
ElseIf 3 = 3 Then
MsgBox ("3=3")
Else
MsgBox ("other")
End If

End Sub
=================================


--ron