check error line number

timj

How can you check the line number of an error if php fails in such a way that a blank page is given? So there are no warnings or error messages (even with the flag display_errors on), but I'd like to know what exactly php does/calculates and/or on which line it fails.

HalfaBee

You might find the error is in the error_log on your server.

HalfaBee

timj

Sorry, the php errorlog does not contain anything.

HalfaBee

It is probably a scripting problem not a php error.

HalfaBee

timj

Thanks for your quick replies.
What do you mean with a "scripting problem"?
All my other php scripts seem to work just fine.

Is there a way I can test the script outside the website (please note that it requires some form parameters as input)? Perhaps that way, I can get a decent error message (without apache or something else interfering).

Jeb_

What's the error_reporting level?

timj

I found this in php.ini:

error_reporting = E_ALL & ~E_NOTICE

Is that what you asked?

Jeb_

That's exactly what I asked 🙂

That means "Display all errors (E_ALL), except for notice-level errors (&~ E_NOTICE)"

I think it's a script issue - I think the script is succeeding, but it isn't printing anything.

Try forcing an error in your script, eg deliberately leave off a semicolon somewhere. If you get an error, you know at least errors are working.

Then, at the top of your script, use this:

error_reporting(E_ALL); // will display ALL errors (overrides php.ini setting)

If you still get nothing, it's most definitely a script issue. Then you need to start stepping through your code, following where it SHOULD be going, and trying to pinpoint exactly where it goes awry.

timj

I'm sorry, but using the line of code you gave me changed nothing. When I tried to force an error (by leaving off the semicolon), the site reported "Parse error on line 40", while I left out the semicolon on line 39. So the error displaying seems fine to me.

Any ideas? I've already tried to pinpoint the line that causes the error, but I haven't had any luck.
At one time I found the following line to be the cause, but it worked fine before (we recently upgraded php and apache), so I don't know if this is really the problem. I thought substr( ) was the cause, but it seems to work fine on other lines of code, so I'm quite puzzled.

$day1=intval(substr($Maps[$i],-7,2))-1;

where $Maps[$i] is the filename of a certain image, as read in from a plain ASCII file.

Weedpacket

Try putting some echo statements in judicious places around the script to give a running commentary on what's going on:

echo "Getting thy Maps array<br>";
//code to get the Maps array
echo "Got thy Maps array<br>";

etc.

And see if they are output.

As for deliberately throwing a Notice (eith error reporting set to E_ALL), have a line
echo $a_totally_spurious_variable;
somewhere. That should throw one.

Meanwhile, I personally set error_reporting in php.ini to E_ALL anyway.

timj

I put

echo $dummy;

just after

error_reporting(E_ALL);

But it does give anything (no notice).

Echo-ing just before and after reading the file that contains the list of image filenames (the Maps array), does not work either (no output at all, just a blank page).

Weedpacket

Originally posted by timj
I put
echo $dummy;
just after
error_reporting(E_ALL);
But it does give anything (no notice).[/B]

At this point I have to start wondering if PHP is even running (my sample referring to Maps was just an example based on the only code sample you've supplied).

You're not buffering output? (ob_start() etc. in the script, output_buffering, output_handler in php.ini?) I half-doubt that could be the problem, though, because the buffer should be flushed at the end of the script, error messages and all, if you don't flush it yourself.

laserlight

hmm... PHP should be running, since there was a parse error reported when a semi-colon was deliberately removed.

timj

I am currently using an output handler, but even without it, the result is still the same.
I don't use ob_start( ), because I don't even have a clue as to what it does (I'll need to check the PhP manual for that).

In php.ini however, I found the following:
output_buffering = On
but I think this was set so that the output_handler would work.

Weedpacket

Originally posted by laserlight
hmm... PHP should be running, since there was a parse error reported when a semi-colon was deliberately removed.

I know, that's what's weird; but when all error messages were turned on and an uninitialised variable was used, there should have been a notice.

The difference of course is that in the event of a parse error the script doesn't run at all (processing stops at the compilation stage), while in the case of a notice the script does run.

Which narrows the problem down to something that is happening within the script. HalfaBee suspected as much, and I think this confirms it (a failure at a lower level would not see parse errors being printed). I've suggested putting more commentary in to announce what's happening as it happens, and so see where it stops. Without actually seeing some code I can't really tell much more.

timj

I suspect the error being in the following section of code (possibly in the $day1= or $day2= lines):

$day1=intval(substr($Maps[$i],-7,2))-1;
         $day2=intval(substr($Maps[$i],-7,2))+1;
         $mm=substr($Maps[$i],-10,2);
	 /*DEBUG: this was used to test the indexes of substr() for $mm*/
	 /*print("MM: $mm MAP $Maps[$i]\n");*/
         $yyyy=substr($Maps[$i],-15,4);
         $datestr=$yyyy."_".$mm;
         print("titleArray[".$j."]='GOME SO2, ".$day1."-".$day2." ".$month[intval($mm)-1]." ".$yyyy."';\n");
         $nItem=count($legend[$mapType][$dirname]["sdate"]);
         $cbfound=0;
         /*DEBUG*/
         /*print("ITEMS: ".$nItem."\n");*/

     for($k=0;$k<$nItem;$k++)
     {
        if($legend[$mapType][$dirname]["sdate"][$k]<=$datestr && $legend[$mapType][$dirname]["edate"][$k]>=$datestr)
    {
      	print("legendArray[".$j."]='".$legend[$mapType][$dirname]["legend"][$k]."';\n");
	$cbfound=1;
    }
     }
     if($cbfound==0)
     {
   /*you can give an error, specify a default file or an empty string*/
       /*BEST: give a default image, otherwise ZoomAnimation might fail!*/
   /*NO: might be confusing for the user, unless the color bar is clearly marked (eg with a text on it) as "unreliable" or something*/
   print("legendArray[".$j."]='dynapi/ColorBars/CB_Not_Found.gif';\n");
     }