[Resolved] variable scope is driving me mad!

zeb

I must have read over my code a hundred times now (personal limit), and this problem is driving me mad!

The problem is this: I have a form which uses itself as a handler (most of the PHP is at the top). When the page receives the form values as $POST, they are stored into variables. A custom function (which declares the variables global) tests them and cleans them up. Later in page, the form fields are dynamically updated to reflect the new field values by 'echoing' the variables. The problem is that the fields don't reflect the new cleaned-up values. Instead they reflect the same original values set at the top from the $POST array. I know that the code which inserts the values into the form fields works because I tried this:

// this is the very top of the page
$name = $_POST['name'] . 'hello';
$email = $_POST['email'] . 'heyThere';

and the 'hello' and 'heyThere' get into the fields. It seems as though the values within the function aren't being made available to the rest of the script. (I do use global for those of you who are thinking...)

The code is quite long, so I'll try to recap:

<?php 

// define the variables
$name = $_POST['name'];
$email = $_POST['email'];
$message = $_POST['message'];
$formSubmitted = $_POST['formSubmitted'];

$sent = 'no';

if ($formSubmitted == 'yes')
	{$feedback = contact_info();
	$feedback_str = "<span class=\"errorMessage\">$feedback</span><br><br>";}
else
	{$feedback_str = '';}


// for use with contact_info()
function clean_up($input)
	{$step1 = stripslashes($input);
	$step2 = strip_tags($step1);
	$step3 = trim($step2);
	return $step3;}


function contact_info()
	{global $name, $email, $message, $sent;

// all sorts of things happen in here... but here are the important lines:

$name = clean_up($name);
$email = clean_up($email);
$message = clean_up($message);

// if everything passes, then do this:
$sendmail = mail($myAddress, $subject, $body, "From: $email");
if ($sendmail)
	{$sent = 'yes';
	$feedback = 'your message has been sent - thank you!';
	return $feedback;}
else
	{$feedback = 'your message could not be sent - try back later';
	return $feedback;}
}


?>
<html>
	<allSortsOfCrap>
	</allSortsOfCrap>
	<form action="... name="...>
		<input type="text" name="name" <?php 
			echo 'value="';
			if ($sent == 'no')
				{echo $name, '"';}
			else
				{echo '"';} ?> size="42">
		<input type="text" name="email" <?php
			echo 'value="';
			if ($sent == 'no')
				{echo $email, '"';}
			else
				{echo '"';} ?> size="42">
		<textarea name="message" rows="6" cols="42"><?php
			if ($sent == 'no')
				{echo $message;} ?></textarea>
		<input type="hidden" name="formSubmitted" value="yes">
	</form>
</html>

So, the $name, $email, and $message in the form fields within the HTML, are using the values stored on the first few lines instead of the values from the function.

I have tried everything! (I think...)

Can anyone see any potential problems?

dalecosp

I have tried everything ( I think )

Does that include passing the vars to the function explicitly?

function contact_info($name, $email, $message) {

🙂

zeb

Actually, no. I have been trying to avoid that. I guess I should have given a bit more info... [just came from BuzzLY's 'netiquette' thread] 😉

I am trying to avoid passing the variables directly because I know I don't need to. I have been doing a very similar thing on other pages - and it works on them, but for some reason it doesn't work on this page.

Consider the following script, which is essentially set up the same way as mine:

$value = 'dumbfounded';

$didItWork = tester();

function reverser($input)
	{$output = strrev($input);
	return $output;}

function tester()
	{global $value;
	$value = reverser($value);
	$feedback = 'yes, it did work';
	return $feedback;}

echo 'did it work? ', $didItWork, '<br>';
echo 'value: ', $value, '<br>';

It outputs this:

did it work? yes, it did work
value: dednuofbmud

The variables are bound at the very top of the script, before the function call. The purpose of the function is its return value and its side effects. The variables are declared global in the function, altered in the function, and then called later in the script. I can't see any reason why the values I get are still the original values assigned at the top.

I have tried setting the variables inside the function (but then the variables in the form fields show up blank - as if they aren't getting out of the function).

I have tried not making a call to the clean_up() function and instead directly reassiging the variable... that didn't work (which indicated that the clean_up() function isn't the culprit.)

I have tried assigning the "cleaned-up" values to new variables, declaring them at the top of the function, and calling them in the form fields... no go.

When I enter 'my <name> is zeb', I should get this: 'my is zeb', but the values are still being displayed unaltered. 😕

laserlight

In that case, I suggest passing the variables by value (or by reference if you need to) rather than declaring global, except for cases where it really is more convenient or obvious.

It's not so much a case of "dont need to" but a case of easier maintenance, and in your case, it should solve your problem.

A possible case of maintainence would be if you're working with a long script that isnt your own, and cant figure out why a particular variable doesnt have what you think it should have, only to discover that the original author happened to have some function somewhere (an included file?) that declared it global and changed it under your nose.

zeb

Originally posted by laserlight
In that case, I suggest passing the variables by value (or by reference if you need to) rather than declaring global, except for cases where it really is more convenient or obvious.

It's not so much a case of "dont need to" but a case of easier maintenance, and in your case, it should solve your problem....

I will probably end up passing the variables explicitly, that is, if no one can see any reason why this script shouldn't work. But if I do that, this problem will always haunt me. It SHOULD work. Right?

As far as easier maintenance... IMHO, it is easier to have variables declared global and weave them in and out of functions as needed.

BTW, what did you mean 'by reference'?

laserlight

"IMHO, it is easier to have variables declared global and weave them in and out of functions as needed."

no it is not.
in some cases yes, but generally using global variables that way makes it more difficult to write modular or object oriented code.

By reference meaning using the & operator.

zeb

Originally posted by laserlight
no it is not.
in some cases yes, but generally using global variables that way makes it more difficult to write modular or object oriented code.

By reference meaning using the & operator.

okay, I won't argue with you. I haven't gotten to the OOP chapter yet, and I will surely understand your point when I get there. 😃

zeb

This is crazy!! :mad:

I have recoded for passing the values in an array explicitly, but I am getting the same type of problem!

The new code looks something like this:

<?php 

// define the variables
$vars['name'] = $_POST['name'];
$vars['email'] = $_POST['email'];
$vars['message'] = $_POST['message'];
$vars['sent'] = 'no';
$formSubmitted = $_POST['formSubmitted'];


if ($formSubmitted == 'yes')
	{$newVars = contact_info($vars);
	$feedback_str = "<span class=\"errorMessage\">$newVars['feedback']</span><br><br>";}
else
	{$feedback_str = '';}


// for use with contact_info()
function clean_up($input)
	{$step1 = stripslashes($input);
	$step2 = strip_tags($step1);
	$step3 = trim($step2);
	return $step3;}


function contact_info($args)
	{

// all sorts of things happen in here... but here are the important lines:

$args['name'] = clean_up($args['name']);
$args['email'] = clean_up($args['email']);
$args['message'] = clean_up($args['message']);

// if everything passes, then do this:
$sendmail = mail($myAddress, $subject, $body, "From: $email");
if ($sendmail)
	{$args['sent'] = 'yes';
	$args['feedback'] = 'your message has been sent - thank you!';
	return $args;}
else
	{$args['feedback'] = 'your message could not be sent - try back later';
	return $args;}
}


?>
<html>
	<allSortsOfCrap>
	</allSortsOfCrap>
	<body>
		// I added this this to see what was happening...
		<?php
		echo "vars array:<br>";
		foreach($vars as $a)
			{echo '&nbsp;&nbsp;', key($vars), ': ', $a, '<br>';
			next($vars);}
		echo "newVars array:<br>";
		foreach($newVars as $b)
			{echo '&nbsp;&nbsp;', key($newVars), ': ', $b, '<br>';
			next($newVars);}
		?>



<form action="... name="...>
	<input type="text" name="name" <?php 
		echo 'value="';
		if ($newVars['sent'] == 'no')
			{echo $newVars['name'], '"';}
		else
			{echo '"';} ?> size="42">
	<input type="text" name="email" <?php
		echo 'value="';
		if ($newVars['sent'] == 'no')
			{echo $newVars['email'], '"';}
		else
			{echo '"';} ?> size="42">
	<textarea name="message" rows="6" cols="42"><?php
		if ($newVars['sent'] == 'no')
			{echo $newVars['message'];} ?></textarea>
	<input type="hidden" name="formSubmitted" value="yes">
</form>
</html>

after submitting the following values (deliberatly with the angle brackets):

name: zeb <b>ellis</b>
email: me@myhost.com
message:

I get a warning that the index 'feedback' is undefined (on line 13 above - starting with the '<?php' as line 1) Yet the output I added at the top of the HTML displays this:

vars array:
name: zeb ellis
email: me@myhost.com
message:
sent: no
newVars array:
name: zeb ellis
email: me@myhost.com
message:
sent: no
feedback: please enter a message

As you can see, the index 'feedback' is defined for this snippet, but not anywhere else... It seems like PHP is not parsing the code directly from top to bottom.

I have NO IDEA what is going on! Any more suggestions??

bad76

Hi,
your code on my personal pc work fine.
This tell me that may be a problem of configuration (are global off?).

As you use $_POST try to use $GLOBALS array...

From manual:

<?php
$a = 1;
$b = 2;

function Sum()
{
    $GLOBALS["b"] = $GLOBALS["a"] + $GLOBALS["b"];
} 

Sum();
echo $b;
?>

// this will echo 3

ahundiak

The original code looks like it should work to me.

$_POST is fine, no need to use $GLOBAL. And there is really no need to get into passing stuff by reference or using an array.

But I gather that what you posted is just part of the script. The problem is probably somewhere in the code you did not paste.

I would recommend that you take the original posted code, add a submit button to the form and then get it to work. Then start adding in the rest of the code a few lines at a time.

And add a few echo statements just to verify that contact_info() and clean_up() are actually being called. I think you will find that clean_up() was not actually being called for some reason.

zeb

Well, I figured it out. The part of the script where I say '// all sorts of things happen in here... but here are the important lines:'... the function performs a bunch of tests and returns a feedback string. I completely overlooked the fact that since the function is stopping at the return line, the variable clean_up() function is never called. So the original script (with the global declaration) would have worked had I moved the clean_up() section to the top of the function.

Laserlight, I have taken your advice and converted a few of my scripts over to passing variable by value. Actually I'm passing all variables in an array. You are right, this will be much easier to manage as I can pass the one array variable to each function, add/change values as I need, and return the array variable at the end. Much nicer! 🙂

When I first switched over to doing this I was having a problem where it seemed like certain values in the passed array, would appear to be defined in some places, and not defined later on in the output... As it turns out, in the places where the value was claiming to be undefined, I was calling the array variables inside double quotes, I didn't realize that PHP needs these to be braced.

// I figured that this would work:
echo "<span class='errorMessage'>$newVars['feedback']</span>";

// turns out it needs to be written like this:
echo "<span class='errorMessage'>{$newVars['feedback']}</span>";

Anyway, thanks for all you help.