Typecast problem in PHP 5.0.4

[Manikandan]

Hi,

I am using the following snippet to compare an object with integer in
my script.

if ( $forecast['day_sequence'] < 4 ) {

I got the "segmentation fault" error message when i executed this
script in CLI. After debugging, i had changed my code to

if ( (int) $forecast['day_sequence'] < 4 ) {

and its worked well. So its means my php version dont do typecasting
automatically it seems.

Is it true?

--
Mani

[Alvaro G. Vicario]

*** Manikandan escribió/wrote (30 Aug 2006 04:43:29 -0700):

if ( $forecast['day_sequence'] < 4 ) {

I got the "segmentation fault" error message when i executed this
script in CLI. After debugging, i had changed my code to

if ( (int) $forecast['day_sequence'] < 4 ) {

and its worked well. So its means my php version dont do typecasting
automatically it seems.

Is it true?

Nope. A segmentation fault is normally a bug in the PHP interpreter or some
other system library. Bad code may help to trigger it some times but it's
always an unexpected result: ideally, PHP should complain if necessary but
not crash.

I've tried this code:

<?php

class Foo{
}

$foo=new Foo();

if($foo < 4){
echo "foo is less than four\n";
}

?>

The condition is true and it also raises a notice: "Notice: Object of class
Foo could not be converted to int"

--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
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--

[Mani]

Hi

Thnks for ur reply.

Nope. A segmentation fault is normally a bug in the PHP interpreter or some
other system library. Bad code may help to trigger it some times but it's
always an unexpected result: ideally, PHP should complain if necessary but
not crash.

Bad code in the sense... i ddint get ur point. Can you explain more
about segmentation fault?

You mentioned that automatic typecast wont raise segmentation error,
then how come after doing only explicit typecast in the code it worked
well

or

The condition is true and it also raises a notice: "Notice: Object of class
Foo could not be converted to int"

Will there any difference between class object and xml object?

If this is simple question, please forgive and help me to know about
this fact.

--
Mani

[Alvaro G. Vicario]

*** Mani escribió/wrote (2 Sep 2006 01:52:33 -0700):

Bad code in the sense... i ddint get ur point. Can you explain more
about segmentation fault?

You mentioned that automatic typecast wont raise segmentation error,
then how come after doing only explicit typecast in the code it worked
well

Alright, let's use a non-programming example. Suppose you're typing a
dossier in Microsoft Word. You need to highlight an specific paragraph so
select the text and press the "bold" toolbar button. And then you get a
message that says "Application performed an illegal operation and will be
shut down" and Word crashes. Does it mean there's something wrong in using
bold fonts in documents? Obviously not!

>The condition is true and it also raises a notice: "Notice: Object of class
Foo could not be converted to int"

Will there any difference between class object and xml object?

I thought you used word "object" in PHP context. Never mind, whatever an
object is for you, it doesn't make any sense to cast it to integer. It's
like checking whether a JPEG picture is greater or equal than zero, it's
total nonsense.
--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Mani]

Hi

Thnks for your reply.

I understood the point explained by you and have to learn good
programming style.

I am in a situation to do further process only if it is less than 4 so
i need to compare in better way not like the existing code. Can you
suggest how to write alternative code for the following snippet?

if ( (int) $forecast['day_sequence'] < 4 ) {

--
Mani
Alvaro G. Vicario wrote:

*** Mani escribió/wrote (2 Sep 2006 01:52:33 -0700):

Bad code in the sense... i ddint get ur point. Can you explain more
about segmentation fault?

You mentioned that automatic typecast wont raise segmentation error,
then how come after doing only explicit typecast in the code it worked
well

Alright, let's use a non-programming example. Suppose you're typing a
dossier in Microsoft Word. You need to highlight an specific paragraph so
select the text and press the "bold" toolbar button. And then you get a
message that says "Application performed an illegal operation and will be
shut down" and Word crashes. Does it mean there's something wrong in using
bold fonts in documents? Obviously not!

The condition is true and it also raises a notice: "Notice: Object of class
Foo could not be converted to int"

Will there any difference between class object and xml object?

I thought you used word "object" in PHP context. Never mind, whatever an
object is for you, it doesn't make any sense to cast it to integer. It's
like checking whether a JPEG picture is greater or equal than zero, it's
total nonsense.
--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Alvaro G. Vicario]

*** Mani escribió/wrote (2 Sep 2006 22:38:05 -0700):

I am in a situation to do further process only if it is less than 4 so
i need to compare in better way not like the existing code. Can you
suggest how to write alternative code for the following snippet?

if ( (int) $forecast['day_sequence'] < 4 ) {

Did you write this code yourself or is it a snipped you copied from
somewhere? It seems that you don't have the faintest idea of what
forecast['day_sequence'] is ... :-?

--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Mani]

I didnt copied and it was written by me. $forecast is an xml element
and 'day_sequence' is an attribute in it and am using simplexml to
parse the document.

For ex, the structure is

<forecast day_sequence = "4" />

Hope the above info will get you to give me the solution.

--
Mani
Alvaro G. Vicario wrote:

*** Mani escribió/wrote (2 Sep 2006 22:38:05 -0700):

I am in a situation to do further process only if it is less than 4 so
i need to compare in better way not like the existing code. Can you
suggest how to write alternative code for the following snippet?

if ( (int) $forecast['day_sequence'] < 4 ) {

Did you write this code yourself or is it a snipped you copied from
somewhere? It seems that you don't have the faintest idea of what
forecast['day_sequence'] is ... :-?

--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Alvaro G. Vicario]

*** Mani escribió/wrote (5 Sep 2006 01:18:02 -0700):

I didnt copied and it was written by me. $forecast is an xml element
and 'day_sequence' is an attribute in it and am using simplexml to
parse the document.

For ex, the structure is

<forecast day_sequence = "4" />

Hope the above info will get you to give me the solution.

A guess: the XML file is somehow large. The fact that it crashes in that
very line is pure chance. I faced such problem not long ago.

Does it happen too if you parse a small XML file?

--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Mani]

Alvaro G. Vicario wrote:

*** Mani escribió/wrote (5 Sep 2006 01:18:02 -0700):

I didnt copied and it was written by me. $forecast is an xml element
and 'day_sequence' is an attribute in it and am using simplexml to
parse the document.

For ex, the structure is

<forecast day_sequence = "4" />

Hope the above info will get you to give me the solution.

A guess: the XML file is somehow large. The fact that it crashes in that
very line is pure chance. I faced such problem not long ago.

Does it happen too if you parse a small XML file?

No its not a large file and infact the xml document has only 6 forecast
element with about 20 attributes in each.

Do you think it is big?

--
Mani

[Alvaro G. Vicario]

*** Mani escribió/wrote (7 Sep 2006 04:50:45 -0700):

No its not a large file and infact the xml document has only 6 forecast
element with about 20 attributes in each.

Do you think it is big?

It depends on the size of the forecast, I suppose. My original XML file had
about 7,000 items and the script crashed with all test file larger than
2,000. Just a guess, as I said ;-)
--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Mani]

It is very small when comparing to ur small file itself.

So ur point is, only because of larger filesize it is showing
"segmentation fault" error not with my comparison of xml object with an
integer

Am i right?

--
Mani

Alvaro G. Vicario wrote:

*** Mani escribió/wrote (7 Sep 2006 04:50:45 -0700):

No its not a large file and infact the xml document has only 6 forecast
element with about 20 attributes in each.

Do you think it is big?

It depends on the size of the forecast, I suppose. My original XML file had
about 7,000 items and the script crashed with all test file larger than
2,000. Just a guess, as I said ;-)
--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--

[Alvaro G. Vicario]

*** Mani escribió/wrote (7 Sep 2006 21:10:33 -0700):

So ur point is, only because of larger filesize it is showing
"segmentation fault" error not with my comparison of xml object with an
integer

Am i right?

Actually, we don't have the faintest idea of why it crashes. The cast
operation maybe the cause... or not. I pointed a similar case that happened
to me but yours seems to be different.

It's possible that if you upgrade or downgrade your PHP installation this
very same code won't segfault.

--
-+ http://alvaro.es - Álvaro G. Vicario - Burgos, Spain
++ Mi sitio sobre programación web: http://bits.demogracia.com
+- Mi web de humor con rayos UVA: http://www.demogracia.com
--