php references.... missing pointers!

[epimeth]

in C, references are great. you make a variable, reference it elsewhere, and then use pointers to the reference to change things around....

however, it seems that in php things work slightly differently... you make a variable...
say $GLOBALS['testg'] = Array(1,2,3,4);

then you reference it...
say $gtest =& $GLOBALS['testg'];

works great!

$testg[] = 5;
$gtest[] = 6;

now both $gtest and $testg are
Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] =>6 )

so obviously, $gtest and $testg are the same exact thing. now if this were c, I know that $testg is really Array(1,2,3,4,5,6) and that $gtest is really the location where $testg is located... but it seems to work differently in php since

unset($testg);
print_r($gtest);

echoes
Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] =>6 )

so it seems to me that $testg and $gtest are both actually references for some thing I can't see nor have access to since php doesn't have pointers.

and, yes... I tried print_r($GLOBALS['testg']) after unsetting $testg just in case $testg was actually a reference to $GLOBALS['testg']

so.... how do I unset all references to a variable if I don't actually know all the reference names? I was under the impression that by unsetting one, I'd unset them all....

[dalecosp]

Seems a bit curious that I can't find this in the manual. But, the manual's so big and I'm so small.

I can tell you where your array is ... but then, you already know that, don't you...?

Seems that in the $GLOBALS array, references aren't...

[epimeth]

there is no $GLOBALS array

but serisouly... here is another problem I've just ran into that has nothing to do with references, but yes with globals....

echo '1  step: '.$step.'<br />';

function myError($e = ''){
  global $step, $errors;
  echo '2 step: '.$step.'<br />'; //for testing
  $errors .= $e.'<br />';
  $step = 0;
}

in another file, which includes the file that the above is located...

print_r($gRegistration);
myError();
print_r($gRegistration);

another included file (included above the one where the myError function is defined) contains my friendly globals, defined as such:

$gRegistration = Array('step' => 0, 'errors' => '');

foreach ($gRegistration as $key => $value)
  $$key =& $gRegistration[$key];

$step = getPostVar('step', 1);

where getPostVar returns the post variable arg1, or the value of arg2 if arg1 doesn't exist.

WHY IS THE FINAL OUTPUT AS FOLLOWS?!?!?!?!?!

1 step: 1
Array ( [step] => 1 [errors] => )
2 step:
Array ( [step] => 1 [errors] => )

Who must I kill in order to get this to work?!?!?!

[dalecosp]

Originally posted by epimeth
there is no $GLOBALS array

OK, so if I'm responding to a joke, so be it... 😉

Global variables: $GLOBALS
Note: $GLOBALS has been available since PHP 3.0.0.

An associative array containing references to all variables which are currently defined in the global scope of the script. The variable names are the keys of the array.

This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. You don't need to do a global $GLOBALS; to access it within functions or methods.

I'm thinking they need to word this more carefully?

[epimeth]

I can tell you where your array is ... but then, you already know that, don't you...?

I thought you were making a reference to the matrix... sorry 🙂

so yea.... that doesn't help with either question, so if anybody knows the answer(s), I'd be very happy... although I did find a workaround to my second problem...

I defined $gRegistration as
$GLOBALS['gRegistration'] =...;

and then did

global gRegistration;

and then...

functino myError($e = ''){
global $gRegistration;
...
}

and instead of $step and $errors I did $gRegistration['step'] and $gRegistration['errors'], respectively...

so that works, although I'm none the wiser as to why it wasn't before... and even more importantly why I had to say
global $gRegistration;
in globals.php before being able to use it (the foreach thing) when in my first example I could use $testg without saying
global $testg;

I am not a happy coder....

[ahundiak]

Just because you stick something in $GLOBALS does not automatically mean that you can access it from inside a function. Wish it did.

So:

$GLOBALS['hello'] = 'Hi There';
function print_hello1()
{
  echo $hello;  /* Won't do much good */
}

$hello = 'Hi There';  /* No need to actually assign to globals */
function print_hello2()
{
  global $hello;  /* Always need this */
  echo $hello;  /* This works */
}

Don't know the answer to the reference problem. You are correct in saying that both variables are in fact references to some unaccessible thing. The manual seems to say that you cannot automatically unset all of the references,
http://www.php.net/manual/en/language.references.unset.php

I think think you may need to change your design. Initialize the variables to null and check for null instead of using isset.

[epimeth]

ahundiak... I appreciate your good intentions, and indeed you did answer the first of my questions, but I must ask you to go back and reread my second post.

let me make it slightly easier on you by telling you to scroll to the top of the page, press ctrl+f and type in the phrase "global $step, $errors;" (no parens), and click ok. this will take you to a line in my code that should do the same thing as your 'global $hello;', yet does not.

do you know why? I certainly don't.

[ahundiak]

I'll tell you what. Boil down your second post into a few lines of code and then I'll look more closely. I can't tell if it's some kind of include file issue or if something else is going on.

[epimeth]

here it is... nice and simple....

globals.php

 
$gRegistration = Array('step' => 0, 'errors' => ''); 

foreach ($gRegistration as $key => $value) 
  $$key =& $gRegistration[$key]; 

$step = getPostVar('step', 1);

functions.php

 
echo '1  step: '.$step.'<br />'; 

function myError($e = ''){ 
  global $step, $errors; 
  echo '2 step: '.$step.'<br />'; //for testing 
  $errors .= $e.'<br />'; 
  $step = 0; 
}

index.php

 
include (globals.php);
include (functions.php);

print_r($gRegistration); 
myError(); 
print_r($gRegistration);

OUTPUT

1 step: 1 
Array ( [step] => 1 [errors] => ) 
2 step: 
Array ( [step] => 1 [errors] => ) 

why aren't the global $step and $errors being accessed in myError()?

thanks in advance

[ahundiak]

Putting your code in one file:

<?php
$gRegistration = Array('step' => 0, 'errors' => '');

foreach ($gRegistration as $key => $value)
  $$key =& $gRegistration[$key];

$step = 1;

echo '1  step: '.$step.'<br />';

function myError($e = '')
{
  global $step, $errors;
  echo '2 step: '.$step.'<br />'; //for testing
  $errors .= $e.'<br />';
  $step = 0;
}
print_r($gRegistration);
myError();
print_r($gRegistration);
?>

It works fine. What version of php are you using?

[epimeth]

php version 4.2.3

honestly, mate... if I wanted the code in one file I'd have done just that.

functions.php has a lot more functions than myError.
globals.php has many more globals.
index.php (which is really block.html) though still quite small, does more than just test myError()... in fact, myError doesn't get called there at all.

not to mention the fact that there are four pages of content dynamically included, depending on what step you are in.

did you test it out using three pages, too? I'd like to know if that works for you...

[Sxooter]

The included file does have

<?php ?>

tags in it right?

[epimeth]

😕 what are <?php ?> tags? :eek:

lol

yes, it does...

[Sxooter]

Well, you're supposed to quote args to include. My machine misinterpreted the first include as referincing a constant.

My version of PHP (4.2.2) can't find the function getpostvar().

[ahundiak]

It works fine with includes. I just used an assignment instead of getPostVars.

epimeth,
As you start to gain experience as a developer you will begin to understand the importance of isolating problems into small test cases. In this case you have a big application which does not work as expected. You now have a small file which does work.

Now take this file and go ahead and include just your globals.php. Does it still work? If no, then start commenting out or going through the file and try to isolate the problem.

If it does work then bring in the functions.php and test it.

Take it in small chunks and the problem will soon be resolved.

[epimeth]

Sxooter... getposvars is a function from the cms I'm using...

ahundiak... I was using small test cases... everything else in the other files was commented out! but thanks for the tip, anyway 🆒

anyway, I got it working by using global $gRegistration instead of $step and $errors... and used $gRegistration['step'] and $gRegistration['errors'] so it really isn't a problem anymore... so it really hasn't been a problem... I just wanted to know if anybody could tell me what was happening...