Unsupported operand types: help!

[stevieontario]

Afternoon Freaks,

 

I have a script that dies at this point: 

			if ($a != 0)
					$ratio = $a/$b;

My script is supposed to process a bunch of XML, almost all of which is numerical (digits). However, at one point in the XML file, the value that $a represents is "N/A".

 

The script dies when it tries to execute line 128, i.e. at $ratio = $a/b;

 

The error message reads: 

 

"Fatal error: Unsupported operand types in /[path/file.php] on line 128"

 

My layman's guess is that php doesn't know what to do when I tell it to divide some number by "N/A".

 

Any ideas?

[stevieontario]

sorry, should have said php does not know what to do when I tell it to divide "N/A" by some number.

[Ch0cu3r]

Why are you dividing a string with a number?

[gizmola]

Correct -- you can't divide "N/A" by a number.  What do you want to happen in these cases?  You could first off check if it is a number with a php function like http://php.net/manual/en/function.is-numeric.php

 

You could also force php to cast "N/A" to an integer or a real, which would be 0.

 

 

$ratio = (float)$a/$b;

 

...or you could have some code like this:

 

 

$a = ($a == 'N/A' ? 1 : $a);

[Barand]

You could use

$a = intval($a);

first, which will give 0 if $a is "N/A";

 

You also need to check if $b==0 or you will get "division by zero" error

[AbraCadaver]

I would use floatval() or (float), and this will test that both need to be a number greater than 0:

if((float)$a && (float)$b) echo $ratio = $a/$b;

Edited October 10, 2013 by AbraCadaver

[stevieontario]

thanks everyone. How about if a value is just empty? I neglected to view the source of the XML table. In source files that work, here's how the XML looks: 

<Output>
<Hour>1</Hour>
<Energy>0</Energy>
</Output>

... and here's how it looks when I'm getting that error:

<Output>
<Hour>1</Hour>
</Output>

i.e., there is no Energy data. Not even a tag. Somehow, that translates into "N/A" on the web table.

 

How do I handle this? My script is looking for some data in the Energy tag, but there isn't even an Energy tag.

[Barand]

perhaps

$str = "<Data>
<Output>
<Hour>1</Hour>
<Energy>0</Energy>
</Output>

<Output>
<Hour>1</Hour>
</Output>
</Data>";

$xml = simplexml_load_string($str);
foreach ($xml->Output as $op) {
    $hr = isset($op->Hour) ? $op->Hour : 0;
    $en = isset($op->Energy) ? $op->Energy : 0;
    $ratio = floatval($hr) && floatval($en) ? $en/$hr : 0;
    echo $ratio.'<br>';
}

Edited October 10, 2013 by Barand

[stevieontario]

thanks again everyone. Barand, using isset() might just solve my problem. Newbie question (VERY newbie) though: can I mix object oriented syntax in with conventional? i.e. I have been denoting arrays using $k => $v syntax

[Barand]

I could have used

foreach ($xml->Output as $k => $op)

but as $k would be unused it wasn't worth the huge extra effort