[Resolved] Using Eval()

[tomwerner]

I am having some problems using the eval function in my calendar script. I am using eval when printing out the loop to determine whether that day should be linked to details or not. The data is stored in a file, 1 line = 1 record, each element of that row is seperated by %^. After some work with arrays the data is stored like so:

$event[$x]["day"]
$event[$x]["month"]
$event[$x]["title"]
$event[$x]["year"]

The thing is that the eval() call spits out an error. Any ideas?
Here is the source:

$x = 0;
		$count = count($event);
		while($x <= $count) {
		$dateinfo .= 'if($x == $event[$x]["day"] & $month == $event[$x]["month"] & $year == $event[$x]["year"]){
 $link="Popup(\'cal_dwnld_popup.php?month=$event[\"{$x}\"][\"month\"]&year=$event[$x][\"year\"]&title=$event[$x][\"title\"]\');"; 
} else {';
		$x++;
		}

	$x = 0;
	$count = count($event);
	$count + 1;
	while($x <= $count) {
	$dateinfo .= '}';
	$x++;
	}

// The eval call
eval($dateinfo);

Here is the $dateinfo (used by eval) echoed out:

if($x == $event[$x]["day"] & $month == $event[$x]["month"] & $year == $event[$x]["year"]){ 
$link="Popup('cal_dwnld_popup.php?month=$event[\"{$x}\"][\"month\"]&year=$event[$x][\"year\"]&title=$event[$x][\"title\"]');"; 
} else {
if($x == $event[$x]["day"] & $month == $event[$x]["month"] & $year == $event[$x]["year"]){ 
$link="Popup('cal_dwnld_popup.php?month=$event[\"{$x}\"][\"month\"]&year=$event[$x][\"year\"]&title=$event[$x][\"title\"]');"; 
} else {
if($x == $event[$x]["day"] & $month == $event[$x]["month"] & $year == $event[$x]["year"]){ 
$link="Popup('cal_dwnld_popup.php?month=$event[\"{$x}\"][\"month\"]&year=$event[$x][\"year\"]&title=$event[$x][\"title\"]');"; 
} else {
}
}
}

Any ideas about what is happening would be appreciated. Sorry about the long post but the problem is quite specific.

[leatherback]

Hi,

Have a look at this thread

[tomwerner]

Thanks for the thread leatherback - I had a look, I get the principle of eval but I can't get rid of whatever the bug in my code is.

I have tried tweaking the " and ' by \ them and removing them, changing these gives different outputs which makes me think there is something wrong there.

Find attached the whole script.

[Weedpacket]

Originally posted by tomwerner
The thing is that the eval() call spits out an error. Any ideas?

What is the error that is spat out?

Looking at the generated source:

$event[\"{$x}\"]

looks dodgy: surely $event[$x] would be sufficient there as for everywhere else.

Here's another suggestion: use a for loop, then the code is likely to be a lot cleaner. This is equivalent:

$count = count($event);

for($x=0; $x<=$count; $x++)
{
	$dateinfo .= 'if($x == $event[$x]["day"] & $month == $event[$x]["month"] & $year == $event[$x]["year"]){
$link="Popup('cal_dwnld_popup.php?month=$event[$x][\"month\"]&year=$event[$x][\"year\"]&title=$event[$x][\"title\"]');"; 
} else {';

}

for($x=0; $x<=$count+1; $x++)        

{
	$dateinfo .= '}';
}

// The eval call
eval($dateinfo);

The first loop runs off the end of the $event[] array and the second runs even further.

Also note that because you're using singule-quoted strings, $x won't actually be evaluated: notice in the generated code that all of the tests and resulting code branches are exactly the same.

I'm not even sure that eval() is even needed. What is the actual output you're trying to achieve from all this? Can the same result not be achieved by just running the code rather than building it up in a string and then running it?

[tomwerner]

I have got the code to a stage where no error is returned but nothing is returned which means in my eyes that there must be a logical error compared to a syntax error. I did suddenly remember how the code was supposed to parse the if - $x actually needs to be put in at that stage so I did this:

$dateinfo .= 'if($x == $event["' . $x . '"]["day"] & $month == $event["' . $x . '"]["month"] & $year == $event["' . $x . '"]["year"]){ 
$link = "Popup(\'includes/cal_dwnld_popup.php?month={$event["' . $x . '"]["month"]}&year={$event["' . $x . '"]["year"]}&title={$event["' . $x . '"]["title"]}\');"; 
} else {';

I'm not even sure that eval() is even needed. What is the actual output you're trying to achieve from all this? Can the same result not be achieved by just running the code rather than building it up in a string and then running it?

I think eval() is the only way to go because the code being created will not execute properly until the loop has finished. I know this method works because initially I used a hardcoded string to be eval() 'ed and this worked, so I know it is purely something to do with this code being generated on the fly. I also need this because the person who will be adminstering the site from day to day does not know PHP and wouldn't be able to add the new if statement when a new event is added.

[leatherback]

Please do yoruself a favor, and add some formatting to your code (At least until you have things workg!:

$dateinfo .= '
if($x == $event["' . $x . '"]["day"] & $month == $event["' . $x . '"]["month"] & $year == $event["' . $x . '"]["year"])
  { 
   $link = "
      Popup('includes/cal_dwnld_popup.php?month={$event["' . $x . '"]["month"]}&year={$event["' . $x . '"]["year"]}&title={$event["' . $x . '"]["title"]}');
      "; 
  } 
else 
  {';

What happens after the else?

Oh, by the way..
I am retty sure you can actually do this in the loop. Could you explain what the problem woul dbe of just chucking the whole part in the data retrieval routine?

if($x == $event["' . $x . '"]["day"] & $month == $event["' . $x . '"]["month"] & $year == $event["' . $x . '"]["year"])
  { 
   $link = "
      Popup('includes/cal_dwnld_popup.php?month={$event["' . $x . '"]["month"]}&year={$event["' . $x . '"]["year"]}&title={$event["' . $x . '"]["title"]}');
      "; 
  } 
else 
  {
   }

J.

[tomwerner]

What happens after the else?

The else is left open to allow the next if created on the next step of the loop to be nested. The second loop is used to put the correct number of } to finish of the nested statements.

This is an echo of what $dateinfo contains once the parsing is complete, I can't see any errors.

if($x == $event[0]["day"] & $month == $event[0]["month"] & $year == $event[0]["year"]){ 
$link = "Popup('includes/cal_dwnld_popup.php?month={$event[0]["month"]}&year={$event[0]["year"]}&title={$event[0]["title"]}');"; 
} else {
if($x == $event[1]["day"] & $month == $event[1]["month"] & $year == $event[1]["year"]){ 
$link = "Popup('includes/cal_dwnld_popup.php?month={$event[1]["month"]}&year={$event[1]["year"]}&title={$event[1]["title"]}');"; 
} else {
}
}

[leatherback]

Hi,

If you do the formatting, you see a lot more clearly what is going on.

I think a } is missing just before the second else statement.

But once more.. You can most likely do this more easily, without eval().

ANyway..