Re: [PHP] assignment operator works for comparison??

2001-04-11 Thread Renze Munnik 

Dan wrote:
> 
> This confused me for awhile, because the single equal sign seemed to work
> for comparison, but created inexplicable errors in my programs.  It seems
> strange to me that a successful variable value assignment does not return
> true.
> 
> example:
> 
>  
>  $shiny = 1;
>  if($shiny = 0){ echo("This wont print"); }
>  echo( $shiny ); //this will return 0
> 
> ?>
> 
> --Dan
> 
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Okay...

First:
Checking if $shiny equals 0:

if ($shiny == 0) {

But that's already been discussed.
If you _realy_ want to check if the assignment succeeded:

if (($shiny = 0) == 0) {

Try the following example:

-
$a = "Hello";
$b = "Wold";

if ($b == $a)
  print "Yes, b equals a\n";
else
  print "No, b doesn't equal a\n";

if (($b = $a) == $a)
  print "Yes... now b equals a\n";
else
  print "Oops... b still doesn't equal a!\n";
-

Output will be:

No, b doesn't equal a
Yes... now b equals a

-- 

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**  Renze Munnik
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Re: [PHP] assignment operator works for comparison??

2001-04-11 Thread Harshdeep S Jawanda 

Hi,

Dan wrote:

> >  > if($shiny = 0){
> > This does not compare anyting, it assigns 0 to $shiny
>
> yes i know, but shouldnt this operation return true?

No, it doesn't return true.

The "=" operator returns the value of the expression on its right hand side.
Therefore, the statement given above is equivalent to (as far as the if is
concerned):

 if (0) {

because the "=" operator returns 0, the value on its right hand side.

That is why a statement like:

 a = b = c = 2

sets all the above variables to 2. Otherwise, if it were to operate the way you
think it should, it would set "c" to 2 and "a" and "b" to "true" ;-).

Hope that clears up things for you.

--
Regards,
Harshdeep Singh Jawanda.



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Re: [PHP] assignment operator works for comparison??

2001-04-10 Thread Yasuo Ohgaki 
>  if($shiny = 0)

This line is the same as

if ((shiny = 0) == TRUE)

It's common error with PHP and C.

You could make use of this like

if ($fp = fopen($filename,'r'))

since this is the same as

if (($fp = fopen($filename,'r')) == TRUE)

code after this line is executed when fopen() success to open file.

Regards,

--
Yasuo Ohgaki


""Dan"" <[EMAIL PROTECTED]> wrote in message
9avrti$olc$[EMAIL PROTECTED]">news:9avrti$olc$[EMAIL PROTECTED]...
> This confused me for awhile, because the single equal sign seemed to work
> for comparison, but created inexplicable errors in my programs.  It seems
> strange to me that a successful variable value assignment does not return
> true.
>
> example:
>
> 
>  $shiny = 1;
>  if($shiny = 0){ echo("This wont print"); }
>  echo( $shiny ); //this will return 0
>
> ?>
>
> --Dan
>
>
>
> --
> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
> To contact the list administrators, e-mail: [EMAIL PROTECTED]
>


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Re: [PHP] assignment operator works for comparison??

2001-04-10 Thread Dan 

You are right, thank you.

> It looks to me like the value of an assignment is the value assigned, as
in
> Perl. But I don't know for sure, haven't come across this in the manual.
>
> Kirk
>
> > >  > if($shiny = 0){
> > > This does not compare anyting, it assigns 0 to $shiny
> >
> > yes i know, but shouldnt this operation return true?




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RE: [PHP] assignment operator works for comparison??

2001-04-10 Thread Johnson, Kirk 

It looks to me like the value of an assignment is the value assigned, as in
Perl. But I don't know for sure, haven't come across this in the manual.

Kirk

> -Original Message-
> From: Dan [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, April 10, 2001 3:29 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [PHP] assignment operator works for comparison??
> 
> 
> 
> >
> >  > if($shiny = 0){
> > This does not compare anyting, it assigns 0 to $shiny
> 
> yes i know, but shouldnt this operation return true?

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Re: [PHP] assignment operator works for comparison??

2001-04-10 Thread Dan 


>
>  > if($shiny = 0){
> This does not compare anyting, it assigns 0 to $shiny

yes i know, but shouldnt this operation return true?

>
>  > echo( $shiny ) // this will return 0
> That's normal, you just assign 0 to it ;)
>
> = assignment operator
> == comparison operator
>
> py
>
>
> At 01:53 PM 4/10/01 -0700, you wrote:
> >This confused me for awhile, because the single equal sign seemed to work
> >for comparison, but created inexplicable errors in my programs.  It seems
> >strange to me that a successful variable value assignment does not return
> >true.
> >
> >example:
> >
> > >
> >  $shiny = 1;
> >  if($shiny = 0){ echo("This wont print"); }
> >  echo( $shiny ); //this will return 0
> >
> >?>
> >
> >--Dan
> >
> >
> >
> >--
> >PHP General Mailing List (http://www.php.net/)
> >To unsubscribe, e-mail: [EMAIL PROTECTED]
> >For additional commands, e-mail: [EMAIL PROTECTED]
> >To contact the list administrators, e-mail: [EMAIL PROTECTED]
>
>
> + ==
> + Pierre-Yves Lem@ire
> + E-MedHosting.com
> + (514) 729-8100
> + [EMAIL PROTECTED]
> + ==
>
>
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Re: [PHP] assignment operator works for comparison??

2001-04-10 Thread Pierre-Yves Lemaire 


 > if($shiny = 0){
This does not compare anyting, it assigns 0 to $shiny

 > echo( $shiny ) // this will return 0
That's normal, you just assign 0 to it ;)

= assignment operator
== comparison operator

py


At 01:53 PM 4/10/01 -0700, you wrote:
>This confused me for awhile, because the single equal sign seemed to work
>for comparison, but created inexplicable errors in my programs.  It seems
>strange to me that a successful variable value assignment does not return
>true.
>
>example:
>
>
>  $shiny = 1;
>  if($shiny = 0){ echo("This wont print"); }
>  echo( $shiny ); //this will return 0
>
>?>
>
>--Dan
>
>
>
>--
>PHP General Mailing List (http://www.php.net/)
>To unsubscribe, e-mail: [EMAIL PROTECTED]
>For additional commands, e-mail: [EMAIL PROTECTED]
>To contact the list administrators, e-mail: [EMAIL PROTECTED]


+ ==
+ Pierre-Yves Lem@ire
+ E-MedHosting.com
+ (514) 729-8100
+ [EMAIL PROTECTED]
+ ==


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