And vs. AndAlso, performance??

[A Traveler]

I was just curious if anyone knows how the combinations of And/AndAlso and
Or/OrElse compare in terms of performance.
Which takes more work for the system, performing two evaluations on an And
or performing short-circuiting on an AndAlso?

Purely for enlightenment.

Thanks in advance.

- Arthur Dent.

[Imran Koradia]

Well - both OrElse and AndAlso are short circuit operators. So for OrElse,
if the first condition is met, it won't even check the second one (which
could be a lengthy operation). Similarly, for AndAlso, if the first
condition is not met, it'll break out without even checking the second one.
So in both the short circuit operations, you're saving on the extra
condition check when the first one is satisfied (OrElse) or not satisfied
(AndAlso). So these should give you better performance in general. Note that
its the expressions that are being evaluated that take the processing time
and not the operations performed by the operators themselves (which are
simply boolean operations). Its just the way in which the short-circuit
operators evaluate which gives you a higher probability of better
performance.
hope that helps..
Imran.

"A Traveler" <hi************ *********@yahoo .com> wrote in message
news:u%******** ********@TK2MSF TNGP10.phx.gbl. ..

I was just curious if anyone knows how the combinations of And/AndAlso and
Or/OrElse compare in terms of performance.
Which takes more work for the system, performing two evaluations on an And
or performing short-circuiting on an AndAlso?

Purely for enlightenment.

Thanks in advance.

- Arthur Dent.

[Herfried K. Wagner [MVP]]

"A Traveler" <hi************ *********@yahoo .com> schrieb:

I was just curious if anyone knows how the combinations of And/
AndAlso and Or/OrElse compare in terms of performance.
Which takes more work for the system, performing two evaluations on an And
or performing short-circuiting on an AndAlso?

I would prefer 'AndAlso'/'OrElse' when a logical operation should be done.
Short circuiting is faster in many cases, because often parts of the
expression don't need to be evaluated.

--
Herfried K. Wagner [MVP]
<URL:http://dotnet.mvps.org/>

[Imran Koradia]

Well - both OrElse and AndAlso are short circuit operators. So for OrElse,
if the first condition is met, it won't even check the second one (which
could be a lengthy operation). Similarly, for AndAlso, if the first
condition is not met, it'll break out without even checking the second one.
So in both the short circuit operations, you're saving on the extra
condition check when the first one is satisfied (OrElse) or not satisfied
(AndAlso). So these should give you better performance in general. Note that
its the expressions that are being evaluated that take the processing time
and not the operations performed by the operators themselves (which are
simply boolean operations). Its just the way in which the short-circuit
operators evaluate which gives you a higher probability of better
performance.
hope that helps..
Imran.

"A Traveler" <hi************ *********@yahoo .com> wrote in message
news:u%******** ********@TK2MSF TNGP10.phx.gbl. ..

I was just curious if anyone knows how the combinations of And/AndAlso and
Or/OrElse compare in terms of performance.
Which takes more work for the system, performing two evaluations on an And
or performing short-circuiting on an AndAlso?

Purely for enlightenment.

Thanks in advance.

- Arthur Dent.

[A Traveler]

I dont think i was clear in my question...

I know _both_ OrElse and AndAlso are short-circuit. But take a case where
the time to process the individual conditions is negligible and can be
discounted. Then assume that you will break out on the short-circuit only on
avg about half the time (or less). Will the Also/Else save time in the long
run then?
Im thinking along the lines of database indexes. By basic principles, an
index is a good thing that improves response time when used on a commonly
search field, just like short-circuit logic is a faster op in basic
principle and runs faster. But now, if your db index will only actually hit
about 50% of the time (or less), it essentially becomes useless (and even a
hindrance, for the extra work the db does to maintain it).
Im wondering if the Also/Else operators are affected by any sort of similar
phenomenon, where the % of hits (or some other factor) may degrade the
benefit ofr them and possibly even make it so they are actually slower. This
would, i imagine, have a great deal to do with how they are actually
implemented in the CLR.

CheerZ.
"A Traveler" <hi************ *********@yahoo .com> wrote in message
news:u%******** ********@TK2MSF TNGP10.phx.gbl. ..

I was just curious if anyone knows how the combinations of And/AndAlso and
Or/OrElse compare in terms of performance.
Which takes more work for the system, performing two evaluations on an And
or performing short-circuiting on an AndAlso?

Purely for enlightenment.

Thanks in advance.

- Arthur Dent.

[A Traveler]

I dont think i was clear in my question...

I know _both_ OrElse and AndAlso are short-circuit. But take a case where
the time to process the individual conditions is negligible and can be
discounted. Then assume that you will break out on the short-circuit only on
avg about half the time (or less). Will the Also/Else save time in the long
run then?
Im thinking along the lines of database indexes. By basic principles, an
index is a good thing that improves response time when used on a commonly
search field, just like short-circuit logic is a faster op in basic
principle and runs faster. But now, if your db index will only actually hit
about 50% of the time (or less), it essentially becomes useless (and even a
hindrance, for the extra work the db does to maintain it).
Im wondering if the Also/Else operators are affected by any sort of similar
phenomenon, where the % of hits (or some other factor) may degrade the
benefit ofr them and possibly even make it so they are actually slower. This
would, i imagine, have a great deal to do with how they are actually
implemented in the CLR.

CheerZ.
"A Traveler" <hi************ *********@yahoo .com> wrote in message
news:u%******** ********@TK2MSF TNGP10.phx.gbl. ..

I was just curious if anyone knows how the combinations of And/AndAlso and
Or/OrElse compare in terms of performance.
Which takes more work for the system, performing two evaluations on an And
or performing short-circuiting on an AndAlso?

Purely for enlightenment.

Thanks in advance.

- Arthur Dent.

[Ken Halter]

A Traveler wrote:

I dont think i was clear in my question...

I know _both_ OrElse and AndAlso are short-circuit. But take a case where
the time to process the individual conditions is negligible and can be
discounted. Then assume that you will break out on the short-circuit only on
avg about half the time (or less). Will the Also/Else save time in the long
run then?

As an innocent bystander just browsing this group, I have to add...

"time to process the individual conditions is negligible"

If that's the case, then there's no benefit to short circuits. When the
tests do take considerable time, it makes sense. The code below will
obviously benefit from a short circuit.

If ResultsFromHard DriveSearch(Som eSearchTerm) > 0 And
ResultsFromInte rnetSearch(Some SearchTerm) > 0 Then

On the other hand, the code below won't benefit much.

If X = 1 Or X = 2 Then

fwiw, you can short circuit VB6 by replacing If/Then's with Select Case's

--
Ken Halter - MS-MVP-VB - http://www.vbsight.com
Please keep all discussions in the groups..

[Ken Halter]

A Traveler wrote:

I dont think i was clear in my question...

I know _both_ OrElse and AndAlso are short-circuit. But take a case where
the time to process the individual conditions is negligible and can be
discounted. Then assume that you will break out on the short-circuit only on
avg about half the time (or less). Will the Also/Else save time in the long
run then?

As an innocent bystander just browsing this group, I have to add...

"time to process the individual conditions is negligible"

If that's the case, then there's no benefit to short circuits. When the
tests do take considerable time, it makes sense. The code below will
obviously benefit from a short circuit.

If ResultsFromHard DriveSearch(Som eSearchTerm) > 0 And
ResultsFromInte rnetSearch(Some SearchTerm) > 0 Then

On the other hand, the code below won't benefit much.

If X = 1 Or X = 2 Then

fwiw, you can short circuit VB6 by replacing If/Then's with Select Case's

--
Ken Halter - MS-MVP-VB - http://www.vbsight.com
Please keep all discussions in the groups..

[A Traveler]

Yes, i am aware that if the conditions are negligible, it doesnt make
*practical* sense to bother with short circuiting.
I am not looking for a practical answer to a specific problem though. I am
simply asking whether there are certain conditions (such as hit percentages)
under which an And performs better than AndAlso, due simply to the way _And_
is implemented vs. how _AndAlso_ is implemented. And i dont mean for a
single run, but over the course of a large number of runs, where sometimes
it will short circuit and sometimes it wont.

"Ken Halter" <Ken_Halter@Use _Sparingly_Hotm ail.com> wrote in message
news:ed******** ******@TK2MSFTN GP15.phx.gbl...

A Traveler wrote:

I dont think i was clear in my question...

I know _both_ OrElse and AndAlso are short-circuit. But take a case where
the time to process the individual conditions is negligible and can be
discounted. Then assume that you will break out on the short-circuit only
on avg about half the time (or less). Will the Also/Else save time in the
long run then?

As an innocent bystander just browsing this group, I have to add...

"time to process the individual conditions is negligible"

If that's the case, then there's no benefit to short circuits. When the
tests do take considerable time, it makes sense. The code below will
obviously benefit from a short circuit.

If ResultsFromHard DriveSearch(Som eSearchTerm) > 0 And
ResultsFromInte rnetSearch(Some SearchTerm) > 0 Then

On the other hand, the code below won't benefit much.

If X = 1 Or X = 2 Then

fwiw, you can short circuit VB6 by replacing If/Then's with Select Case's

--
Ken Halter - MS-MVP-VB - http://www.vbsight.com
Please keep all discussions in the groups..

[A Traveler]

Yes, i am aware that if the conditions are negligible, it doesnt make
*practical* sense to bother with short circuiting.
I am not looking for a practical answer to a specific problem though. I am
simply asking whether there are certain conditions (such as hit percentages)
under which an And performs better than AndAlso, due simply to the way _And_
is implemented vs. how _AndAlso_ is implemented. And i dont mean for a
single run, but over the course of a large number of runs, where sometimes
it will short circuit and sometimes it wont.

"Ken Halter" <Ken_Halter@Use _Sparingly_Hotm ail.com> wrote in message
news:ed******** ******@TK2MSFTN GP15.phx.gbl...

A Traveler wrote:

I dont think i was clear in my question...

I know _both_ OrElse and AndAlso are short-circuit. But take a case where
the time to process the individual conditions is negligible and can be
discounted. Then assume that you will break out on the short-circuit only
on avg about half the time (or less). Will the Also/Else save time in the
long run then?

As an innocent bystander just browsing this group, I have to add...

"time to process the individual conditions is negligible"

If that's the case, then there's no benefit to short circuits. When the
tests do take considerable time, it makes sense. The code below will
obviously benefit from a short circuit.

If ResultsFromHard DriveSearch(Som eSearchTerm) > 0 And
ResultsFromInte rnetSearch(Some SearchTerm) > 0 Then

On the other hand, the code below won't benefit much.

If X = 1 Or X = 2 Then

fwiw, you can short circuit VB6 by replacing If/Then's with Select Case's

--
Ken Halter - MS-MVP-VB - http://www.vbsight.com
Please keep all discussions in the groups..